Tumour vasculogenic mimicry is associated with poor prognosis of human cancer patients: a systemic review and meta-analysis

Navigating the tumor landscape: VEGF, MicroRNAs, and the future of cancer treatment

Cancer progression is a multifaceted process influenced by complex interactions within the tumor microenvironment (TME). Central to these dynamics are Vascular Endothelial Growth Factor (VEGF) signalling and microRNA (miRNA) modulation, both of which play critical roles in tumor growth and angiogenesis. VEGF is essential for promoting blood vessel formation; however, its splice variant, VEGF165b, acts as an anti-angiogenic factor, presenting a paradox challenging conventional cancer therapies. Meanwhile, miRNAs regulate gene expression that significantly impacts tumor behaviour by targeting various mRNAs involved in signalling pathways. The interplay between VEGF and miRNAs opens new avenues for targeted therapies designed to disrupt the networks supporting tumor growth. Additionally, the concept of exploiting the unique properties of VEGF splice variants is being explored to develop novel treatments that enhance anti-angiogenic effects while minimizing side effects. Understanding this is crucial for advancing personalized therapies that can effectively address the challenges posed by tumor adaptability and resistance mechanisms.

Current knowledge on the mechanisms underpinning vasculogenic mimicry in triple negative breast cancer and the emerging role of nitric oxide

Vasculogenic mimicry (VM) is the process by which cancer cells form vascular-like channels to support their growth and dissemination. These channels lack endothelial cells and are instead lined by the tumour cells themselves. VM was first reported in uveal melanomas but has since been associated with other aggressive solid tumours, such as triple-negative breast cancer (TNBC). In TNBC patients, VM is associated with tumour aggressiveness, drug resistance, metastatic burden, and poor prognosis. The lack of effective targeted therapies for TNBC has stimulated research on the mechanisms underpinning VM in order to identify novel druggable targets. In recent years, studies have highlighted the role of nitric oxide (NO), the NO synthesis inhibitor, asymmetric dimethylarginine (ADMA), and dimethylarginine dimethylaminohydrolase 1 (DDAH1), the key enzyme responsible for ADMA metabolism, in regulating VM. Specifically, NO inhibition through downregulation of DDAH1 and consequent accumulation of ADMA appears to be a promising strategy to suppress VM in TNBC. This review discusses the current knowledge regarding the molecular pathways underpinning VM in TNBC, anti-VM therapies under investigation, and the emerging role of NO regulation in VM.

Challenges of small cell lung cancer heterogeneity and phenotypic plasticity

Small cell lung cancer (SCLC) is an aggressive neuroendocrine malignancy with ~7% 5-year overall survival reflecting early metastasis and rapid acquired chemoresistance. Immunotherapy briefly extends overall survival in ~15% cases, yet predictive biomarkers are lacking. Targeted therapies are beginning to show promise, with a recently approved delta-like ligand 3 (DLL3)-targeted therapy impacting the treatment landscape. The increased availability of patient-faithful models, accumulating human tumour biobanks and numerous comprehensive molecular profiling studies have collectively facilitated the mapping and understanding of substantial intertumoural and intratumoural heterogeneity. Beyond the almost ubiquitous loss of wild-type p53 and RB1, SCLC is characterized by heterogeneously mis-regulated expression of MYC family members, yes-associated protein 1 (YAP1), NOTCH pathway signalling, anti-apoptotic BCL2 and epigenetic regulators. Molecular subtypes are based on the neurogenic transcription factors achaete-scute homologue 1 (ASCL1) and neurogenic differentiation factor 1 (NEUROD1), the rarer non-neuroendocrine transcription factor POU class 2 homeobox 3 (POU2F3), and immune- and inflammation-related signatures. Furthermore, SCLC shows phenotypic plasticity, including neuroendocrine-to-non-neuroendocrine transition driven by NOTCH signalling, which is associated with disease progression, chemoresistance and immune modulation and, in mouse models, with metastasis. Although these features pose substantial challenges, understanding the molecular vulnerabilities of transcription factor subtypes, the functional relevance of plasticity and cell cooperation offer opportunities for personalized therapies informed by liquid and tissue biomarkers.

IL-1β in Neoplastic Disease and the Role of Its Tumor-Derived Form in the Progression and Treatment of Metastatic Prostate Cancer

Since its discovery, IL-1β has taken center stage as a key mediator of a very broad spectrum of diseases revolving around immuno-mediated and inflammatory events. Predictably, the pleiotropic nature of this cytokine in human pathology has led to the development of targeted therapeutics with multiple treatment indications in the clinic. Following the accumulated findings of IL-1β's central modulatory role in the immune system and the implication of inflammatory pathways in cancer, the use of IL-1β antagonists was first proposed and then also pursued for oncology disorders. However, this approach has consistently relied on the perceived need of interfering with IL-1β synthesized and secreted by immune cells. Herein, we discuss the importance of IL-1β derived from cancer cells which impacts primary tumors, particularly metastatic lesions, separately from and in addition to its more recognized role in immune-mediated inflammatory events. To this end, we focus on the instrumental contribution of IL-1β in the establishment and progression of advanced prostate adenocarcinoma. Special emphasis is placed on the potential role that the standard-of-care treatment strategies for prostate cancer patients have in unleashing IL-1β expression and production at metastatic sites. We conclude by reviewing the therapeutics currently used for blocking IL-1β signaling and propose a rationale for their concomitant use with standard-of-care treatments to improve the clinical outcomes of advanced prostate cancer.

Tumor-Derived Immunoglobulin-Like Transcript 4 Promotes Postoperative Relapse via Inducing Vasculogenic Mimicry through MAPK/ERK Signaling in Hepatocellular Carcinoma

The efficacy of conventional anti-angiogenesis drugs is usually low in treating hepatocellular carcinoma (HCC). Therefore, there is an urgent need to find new precise therapeutic targets and to develop more effective drugs for the treatment of HCC. Vasculogenic mimicry (VM) is different from classic endothelium-dependent angiogenesis and is associated with a poor prognosis in patients with malignant tumor. However, the mechanism underlying VM is complex and not fully defined. Ig-like transcript (ILT)-4, as a negative regulator of immune response, is expressed in many solid tumors. However, whether and how ILT4 regulates VM remains unclear. This study found VM enriched in HCC tissues, especially in tissues from patients with relapse within 5 years after surgery. Similarly, ILT4 expression level was also higher in HCC tissues from patients with relapse within 5 years after surgery. Linear regression analysis revealed a positive correlation between the expression of ILT4 and VM density. Furthermore, overexpression/knockdown of ILT4 expression upregulated/down-regulated VM-related marker, three-dimensional tube formation, and migration and invasion in HCC cell lines in vitro. In mechanistic studies, ILT4 promoted VM formation via mitogen-activated protein kinase (MAPK)/ERK signaling. This study provides a rationale and mechanism for ILT4-mediated postoperative relapse via inducing VM in HCC. The related molecular pathways can be used as novel therapeutic targets for the inhibition of HCC angiogenesis and postoperative relapse.

The vasculogenic mimicry, CD146+ and CD105+ microvessel density in the prognosis of endometrioid endometrial adenocarcinoma: a single-centre immunohistochemical study

The microvessel compartment is crucial in the tumour microenvironment of endometrioid adenocarcinoma (EA). This study investigated the role of vasculogenic mimicry (VM), CD146, and CD105 microvessel density in the clinical prognosis of EA. A total of 188 EA cases were analyzed, with VM channels and microvessels detected using PAS/CD31, CD146, and CD105 staining. Mann-Whitney and Fisher exact tests were used to compare the study groups according to the evaluated criteria. ROC analysis included determination of the confidence interval (CI) and area under the ROC curve. The Mantel-Cox test was used to analyze progression-free survival. Multivariate Cox proportional hazard analysis was performed using stepwise regression. Results showed that VM channels and CD146 and CD105 microvessels were significantly higher (p < 0.0001) in cases with unfavourable prognosis. Univariate survival analysis highlighted the significant role of these factors in progression-free survival, while multivariate Cox analysis identified VM and CD146+ vessels as predictive factors. This study demonstrates, for the first time, that VM, CD146, and CD105-positive vessels are involved in EA prognosis, suggesting their potential as independent prognostic indicators and targets for antiangiogenic therapy. However, these findings require further validation through large-scale studies.

Strong Activation of ID1, ID2, and ID3 Genes Is Coupled with the Formation of Vasculogenic Mimicry Phenotype in Melanoma Cells

Gene expression patterns are very sensitive to external influences and are reflected in phenotypic changes. It was previously described that transferring melanoma cells from a plastic surface to Matrigel led to formation of de novo vascular networks-vasculogenic mimicry-that are characteristic to a stemness phenotype in aggressive tumors. Up to now there was no detailed data about the gene signature accompanying this process. Here, we show that this transfer shortly led to extremely strong epigenetic changes in gene expression in the melanoma cells. We observed that on Matrigel numerous genes controlling ribosome biogenesis were upregulated. However, most of the activated genes were inhibitors of the differentiation genes (ID1, ID2, and ID3). At the same time, the genes that control differentiation were downregulated. Both the upregulated and the downregulated genes are simultaneously targeted by different transcription factors shaping sets of co-expressed genes. The specific group of downregulated genes shaping contacts with rDNA genes are also associated with the H3K27me3 mark and with numerous lincRNAs and miRNAs. We conclude that the stemness phenotype of melanoma cells is due to the downregulation of developmental genes and formation of dedifferentiated cells.

HSP27 promotes vasculogenic mimicry formation in human salivary adenoid cystic carcinoma via the AKT-MMP-2/9 pathway

PURPOSE

To explore the role and mechanism of heat shock protein 27 (HSP27) in SACC VM formation.

STUDY DESIGN

Immunohistochemistry and double staining with cluster of differentiation 31 (CD31) and periodic acid-Schiff (PAS) were used to detect HSP27 expression and VM in 70 SACC tissue samples separately. Quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and immunofluorescence were used to detect gene and protein expression. HSP27 in SACC cells were overexpression or downregulated by transfecting HSP27 or short hairpin RNA target HSP27 (sh-HSP27). The migration and invasion abilities of SACC cells were detected using wound healing and Transwell invasion assays. The VM formation ability of the cells in vitro was detected using a Matrigel 3-dimensional culture.

RESULTS

HSP27 expression was positively correlated with VM formation and affected the prognosis of patients. In vitro, HSP27 upregulation engendered VM formation and the invasion and migration of SACC cells. Mechanistically, HSP27 upregulation increased Akt phosphorylation and subsequently increased downstream matrix metalloproteinase 2 and 9 expressions.

CONCLUSION

HSP27 may plays an important role in VM formation in SACC via the AKT-MMP-2/9 signalling pathway.

Pan-cancer dissection of vasculogenic mimicry characteristic to provide potential therapeutic targets

Introduction

Vasculogenic mimicry (VM) represents a novel form of tumor angiogenesis that is associated with tumor invasiveness and drug resistance. However, the VM landscape across cancer types remains poorly understood. In this study, we elucidate the characterizations of VM across cancers based on multi-omics data and provide potential targeted therapeutic strategies.

Methods

Multi-omics data from The Cancer Genome Atlas was used to conduct comprehensive analyses of the characteristics of VM related genes (VRGs) across cancer types. Pan-cancer vasculogenic mimicry score was established to provide a depiction of the VM landscape across cancer types. The correlation between VM and cancer phenotypes was conducted to explore potential regulatory mechanisms of VM. We further systematically examined the relationship between VM and both tumor immunity and tumor microenvironment (TME). In addition, cell communication analysis based on single-cell transcriptome data was used to investigate the interactions between VM cells and TME. Finally, transcriptional and drug response data from the Genomics of Drug Sensitivity in Cancer database were utilized to identify potential therapeutic targets and drugs. The impact of VM on immunotherapy was also further clarified.

Results

Our study revealed that VRGs were dysregulated in tumor and regulated by multiple mechanisms. Then, VM level was found to be heterogeneous among different tumors and correlated with tumor invasiveness, metastatic potential, malignancy, and prognosis. VM was found to be strongly associated with epithelial-mesenchymal transition (EMT). Further analyses revealed cancer-associated fibroblasts can promote EMT and VM formation. Furthermore, the immune-suppressive state is associated with a microenvironment characterized by high levels of VM. VM score can be used as an indicator to predict the effect of immunotherapy. Finally, seven potential drugs targeting VM were identified.

Conclusion

In conclusion, we elucidate the characteristics and key regulatory mechanisms of VM across various cancer types, underscoring the pivotal role of CAFs in VM. VM was further found to be associated with the immunosuppressive TME. We also provide clues for the research of drugs targeting VM. Our study provides an initial overview and reference point for future research on VM, opening up new avenues for therapeutic intervention.

Inhibition of PD-L1 expression in non-small cell lung cancer may reduce vasculogenic mimicry formation by inhibiting the epithelial mesenchymal transformation process

Non-small cell lung cancer (NSCLC) is a kind of highly malignant tumor. Studies have shown that Vasculogenic mimicry (VM) may be responsible for dismal prognosis in NSCLC. Immunotherapy with programmed death-1 (PD-1) or programmed death ligand-1 (PD-L1) has significantly altered the treatment of assorted cancers, including NSCLC, but its role and mechanism in the formation of Vasculogenic mimicry (VM) in NSCLC remains unclear. This study aimed to investigate the role of the anti-PD-L1 antibody in the formation of VM in NSCLC and its possible mechanisms. The results showed that anti-PD-L1 antibody therapy could inhibit the growth of NSCLC-transplanted tumors and reduce the formation of VMs. In addition, this study found that anti-PD-L1 antibodies could increase the expression of the epithelial-mesenchymal transition (EMT) related factor E-cadherin. zinc finger E-box binding homeobox 1 (ZEB1) is an important transcription factor regulating EMT. Knocking down ZEB1 could significantly inhibit tumor growth, as well as the expression of VE-cadherin and mmp2, while remarkably increase the expression of E-cadherin. During this process, the formation of VM was inhibited by knowing down ZEB1 in both in vitro and in vivo experiments of the constructed ZEB1 knockdown stable transfected cell strains. Therefore, in this study, we found that anti-PD-L1 antibodies may reduce the formation of VMs by inhibiting the EMT process.

Doxazosin inhibits vasculogenic mimicry in human non‑small cell lung cancer through inhibition of the VEGF‑A/VE‑cadherin/mTOR/MMP pathway

Lung cancer is the leading cause of cancer-related death worldwide, and ~85% of lung cancers are non-small cell lung cancer (NSCLC), which has a low 5-year overall survival rate and high mortality. Several therapeutic strategies have been developed, such as targeted therapy, immuno-oncotherapy and combination therapy. However, the low survival rate indicates the urgent need for new NSCLC treatments. Vasculogenic mimicry (VM) is an endothelial cell-free tumor blood supply system of aggressive and metastatic tumor cells present during tumor neovascularization. VM is clinically responsible for tumor metastasis and resistance, and is correlated with poor prognosis in NSCLC, making it a potential therapeutic target. In the present study, A549 cells formed glycoprotein-rich lined tubular structures, and transcript levels of VM-related genes were markedly upregulated in VM-forming cells. Based on a drug repurposing strategy, it was demonstrated that doxazosin (an antihypertensive drug) displayed inhibitory activity on VM formation at non-cytotoxic concentrations. Doxazosin significantly reduced the levels of vascular endothelial growth factor A (VEGF-A) and matrix metalloproteinase-2 (MMP-2) in the cell media during VM formation. Further experiments revealed that the protein expression levels of VEGF-A and vascular endothelial-cadherin (VE-cadherin), which contribute to tumor aggressiveness and VM formation, were downregulated following doxazosin treatment. Moreover, the downstream signaling Ephrin type-A receptor 2 (EphA2)/AKT/mTOR/MMP/Laminin-5γ2 network was inhibited in response to doxazosin treatment. In conclusion, the present study demonstrated that doxazosin displayed anti-VM activity in an NSCLC cell model through the downregulation of VEGF-A and VE-cadherin levels, and the suppression of signaling pathways related to the receptor tyrosine kinase, EphA2, protein kinases, AKT and mTOR, and proteases, MMP-2 and MMP-9. These results support the add-on anti-VM effect of doxazosin as a potential agent against NSCLC.

Advance in the role of chemokines/chemokine receptors in carcinogenesis: Focus on pancreatic cancer

The chemokines/chemokine receptors pathway significantly influences cell migration, particularly in recruiting immune cells to the tumor microenvironment (TME), impacting tumor progression and treatment outcomes. Emerging research emphasizes the involvement of chemokines in drug resistance across various tumor therapies, including immunotherapy, chemotherapy, and targeted therapy. This review focuses on the role of chemokines/chemokine receptors in pancreatic cancer (PC) development, highlighting their impact on TME remodeling, immunotherapy, and relevant signaling pathways. The unique immunosuppressive microenvironment formed by the interaction of tumor cells, stromal cells and immune cells plays an important role in the tumor proliferation, invasion, migration and therapeutic resistance. Chemokines/chemokine receptors, such as chemokine ligand (CCL) 2, CCL3, CCL5, CCL20, CCL21, C-X-C motif chemokine ligand (CXCL) 1, CXCL2, CXCL3, CXCL4, CXCL5, CXCL8, CXCL9, CXCL10, CXCL11, CXCL12, CXCL13, CXCL14, CXCL16, CXCL17, and C-X3-C motif chemokine ligand (CX3CL)1, derived mainly from leukocyte cells, cancer-related fibroblasts (CAFs), pancreatic stellate cells (PSCs), and tumor-associated macrophages (TAMs), contribute to PC progression and treatment resistance. Chemokines recruit myeloid-derived suppressor cells (MDSC), regulatory T cells (Tregs), and M2 macrophages, inhibiting the anti-tumor activity of immune cells. Simultaneously, they enhance pathways like epithelial-mesenchymal transition (EMT), Akt serine/threonine kinase (AKT), extracellular regulated protein kinases (ERK) 1/2, and nuclear factor kappa-B (NF-κB), etc., elevating the risk of PC metastasis and compromising the efficacy of radiotherapy, chemotherapy, and anti-PD-1/PD-L1 immunotherapy. Notably, the CCLx-CCR2 and CXCLx-CXCR2/4 axis emerge as potential therapeutic targets in PC. This review integrates recent findings on chemokines and receptors in PC treatment, offering valuable insights for innovative therapeutic approaches.

CD146+CAFs promote progression of endometrial cancer by inducing angiogenesis and vasculogenic mimicry via IL-10/JAK1/STAT3 pathway

Heterogeneous cancer-associated fibroblasts (CAFs) play important roles in cancer progression. However, the specific biological functions and regulatory mechanisms involved in endometrial cancer have yet to be elucidated. We aimed to explore the potential mechanisms of heterogeneous CAFs in promoting endometrial cancer progression. The presence of melanoma cell adhesion molecule (MCAM; CD146) positive CAFs was confirmed by tissue multi-immunofluorescence (mIF), and fluorescence activated cell sorting (FACS). The biological functions were determined by wound healing assays, tuber formation assays and cord formation assays. The effects of CD146+CAFs on endometrial cancer cells were studied in vitro and in vivo. The expression level of interleukin 10 (IL-10) was measured by quantitative real time polymerase chain reaction (qRT-PCR), western boltting and enzyme linked immunosorbent assays (ELISAs). In addition, the transcription factor STAT3 was identified by bioinformatics methods and chromatin immunoprecipitation (ChIP). A subtype of CAFs marked with CD146 was found in endometrial cancer and correlated with poor prognosis. CD146+CAFs promoted angiogenesis and vasculogenic mimicry (VM) in vitro. A xenograft tumour model also showed that CD146+CAFs can facilitate tumour progression. The expression of IL-10 was elevated in CD146+CAFs. IL-10 promoted epithelial-endothelial transformation (EET) and further VM formation in endometrial cancer cells via the janus kinase 1/signal transducer and activator of transcription 3 (JAK1/STAT3) signalling pathway. This process could be blocked by the JAK1/STAT3 inhibitor niclosamide. Mechanically, STAT3 can bind to the promoter of cadherin5 (CDH5) to promote its transcription which may be stimulated by IL-10. We concluded that CD146+CAFs could promote angiogenesis and VM formation via the IL-10/JAK1/STAT3 signalling pathway. These findings may lead to the identification of potential targets for antiangiogenic therapeutic strategies for endometrial cancers.

Establishment of skin cutaneous melanoma prognosis model based on vascular mimicry risk score

Studies have indicated that Vascular mimicry (VM) could contribute to the unfavorable prognosis of skin cutaneous melanoma (SKCM). Thus, the objective of this study was to identify therapeutic targets associated with VM in SKCM and develop a novel prognostic model. Gene expression data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) were utilized to identify differentially expressed genes (DEGs). By intersecting these DEGs with VM genes, we acquired VM-related DEGs specific to SKCM, and then identified prognostic-related VM genes. A VM risk score system was established based on these prognosis-associated VM genes, and patients were then categorized into high- and low-score groups using the median score. Subsequently, differences in clinical characteristics, gene set enrichment analysis (GSEA), and other analyses were further presented between the 2 groups of patients. Finally, a novel prognostic model for SKCM was established using the VM score and clinical characteristics. 26 VM-related DEGs were identified in SKCM, among the identified DEGs associated with VM in SKCM, 5 genes were found to be prognostic-related. The VM risk score system, comprised of these genes, is an independent prognostic risk factor. There were significant differences between the 2 patient groups in terms of age, pathological stage, and T stage. VM risk scores are associated with epithelial biological processes, angiogenesis, regulation of the SKCM immune microenvironment, and sensitivity to targeted drugs. The novel prognostic model demonstrates excellent predictive ability. Our study identified VM-related prognostic markers and therapeutic targets for SKCM, providing novel insights for clinical diagnosis and treatment.

Vasculogenic mimicry-associated novel gene signature predicted prognosis and response to immunotherapy in lung adenocarcinoma

BACKGROUNDS

It was highlighted by recent studies on the biological significance of vasculogenic mimicry (VM) in tumorigenicity and progression. However, it is unclear whether VM also plays a potential role in immune regulation and tumor microenvironment (TME) formation.

METHODS

To identify patterns of VM alterations and VM-associated genetic features in non-small cell lung adenocarcinoma, we have screened 309 VM regulators and performed consensus molecular typing by the NMF algorithm. The ssGSEA and CIBORSORT algorithms were employed to measure the relative infiltration of distinct immune cell subpopulations. Individual tumors with immune responses were evaluated for alteration patterns of VM with typing-based differential genes.

RESULTS

In 490 LUAD samples, two distinctive VM alteration patterns connected to different clinical outcomes and biochemical pathways were established. TME characterization showed that the observed VM patterns were primarily saturated with cell proliferation and metabolic pathways and higher in immune cell infiltration of the C1 type. Vasculogenic mimicry-related genes (VMRG) risk scores were constructed to divide patients with lung adenocarcinoma into subgroups with high and low scores. Patients with lower scores had better immunological scores and longer survival times. Upon further investigation, higher scores were positively correlated with higher tumor mutation burden (TMB), M1-type macrophages and immune checkpoint molecules. Nevertheless, in two other immunotherapy cohorts, individuals with lower scores had enhanced immune responses and long-lasting therapeutic benefits. Finally, we monitored the ANLN gene from the VMRG model, which was highly expressed in lung adenocarcinoma tissues and negatively correlated with prognosis; it was also highly expressed in lung adenocarcinoma cell lines, and knockdown of ANLN elicited low expression of VEGFA, MMP2 and MMP9.

CONCLUSION

This study highlights that VM modifications are significantly associated with the diversity and complexity of TME, revealing new features of the immune microenvironment in lung adenocarcinoma and providing a new strategy for immunotherapy. Screening ANLN as a critical target for vasculogenic mimicry in lung adenocarcinoma provides a novel perspective for the targeted treatment of lung adenocarcinoma.

Preoperative prediction of vasculogenic mimicry in lung adenocarcinoma using a CT radiomics model

AIM

To develop and validate a non-invasive computed tomography (CT)-based radiomics model for predicting vasculogenic mimicry (VM) status in lung adenocarcinoma (LA).

MATERIALS AND METHODS

Two hundred and three patients with LA were enrolled retrospectively and grouped into training and test groups with a ratio of 7:3. Uni- and multivariate logistic regression analyses were performed in the training cohort to screen the independent clinical and radiological factors for VM, and the clinical model was then established. A radiomics model was established based on the rad-scores through support vector machine (SVM). A radiomics nomogram model was subsequently constructed by combining the rad-score with clinical-radiological factors. The receiver operating characteristic curve (ROC), calibration curves, and decision curve analysis (DCA) were conducted to evaluate the performance of the three models.

RESULTS

Nine selected radiomics features were selected for the radiomics model and the maximum length and spiculation sign were constructed for the clinical model. The radiomics nomogram model integrating the maximum length, spiculation sign, and rad-score yielded the best AUC in both the training (AUC = 0.925) and test cohorts (AUC = 0.978), in comparison with the radiomics model (AUC = 0.907 and 0.964, in both the training and test cohorts) and the clinical model (AUC = 0.834 and 0.836 in both training and test cohorts).

CONCLUSIONS

The CT-based radiomics nomogram model showed satisfying discriminating performance for preoperatively and non-invasively predicting VM expression status in LA patients.

Prostate Cancer Microvascular Routes: Exploration and Measurement Strategies

Angiogenesis is acknowledged as a pivotal feature in the pathology of human cancer. Despite the absence of universally accepted markers for gauging the comprehensive angiogenic activity in prostate cancer (PCa) that could steer the formulation of focused anti-angiogenic treatments, the scrutiny of diverse facets of tumoral blood vessel development may furnish significant understanding of angiogenic processes. Malignant neoplasms, encompassing PCa, deploy a myriad of strategies to secure an adequate blood supply. These modalities range from sprouting angiogenesis and vasculogenesis to intussusceptive angiogenesis, vascular co-option, the formation of mosaic vessels, vasculogenic mimicry, the conversion of cancer stem-like cells into tumor endothelial cells, and vascular pruning. Here we provide a thorough review of these angiogenic mechanisms as they relate to PCa, discuss their prospective relevance for predictive and prognostic evaluations, and outline the prevailing obstacles in quantitatively evaluating neovascularization via histopathological examinations.

Therapeutic potential of vasculogenic mimicry in urological tumors

Angiogenesis is an essential process in the growth and metastasis of cancer cells, which can be hampered by an anti-angiogenesis mechanism, thereby delaying the progression of tumors. However, the benefit of this treatment modality could be restricted, as most patients tend to develop acquired resistance during treatment. Vasculogenic mimicry (VM) is regarded as a critical alternative mechanism of tumor angiogenesis, where studies have demonstrated that patients with tumors supplemented with VM generally have a shorter survival period and a poorer prognosis. Inhibiting VM may be an effective therapeutic strategy to prevent cancer progression, which could prove helpful in impeding the limitations of lone use of anti-angiogenic therapy when performed concurrently with other anti-tumor therapies. This review summarizes the mechanism of VM signaling pathways in urological tumors, i.e., prostate cancer, clear cell renal cell carcinoma, and bladder cancer. Furthermore, it also summarizes the potential of VM as a therapeutic strategy for urological tumors.

Vasculogenic mimicry score identifies the prognosis and immune landscape of lung adenocarcinoma

Background: Lung cancer has a high incidence and mortality rate worldwide. Vasculogenic mimicry (VM) is a specific modality of tumor angiogenesis that could potentially be a new target for tumor therapy. The purpose of this study was to explore the role of VM-related genes in assessing the prognosis and immune landscape of lung cancer. Methods: VM-related genes were obtained from previous studies, and the expression data and clinical data of lung adenocarcinoma (LUAD) patients were obtained from the TCGA database and GEO database. We performed enrichment analysis of 24 VM-related genes and screened hub genes by constructing a protein-protein interaction network and using Cytoscape software. Subsequently, we developed the VM score based on univariate Cox regression analysis and Lasso analysis and validated the VM score on the GSE72094 dataset. In addition, we constructed a nomogram based on the VM score in the TCGA cohort. Finally, we explored the correlation between the VM score and the tumor microenvironment, immune cell infiltration, immune checkpoints, and drug sensitivity. Results: Enrichment analysis revealed that VM-related genes were associated with the HIF signaling pathway and angiogenic pathway. We developed a VM score based on 3 genes (EPHA2, LAMC2 and LOXL2) in LUAD patients. Kaplan-Meier analysis showed that the VM score was associated with poor prognosis in LUAD patients. The receiver operating characteristic curve suggested that the VM score and nomogram are valid predictors for the overall survival of LUAD patients. The VM score was significantly correlated with immune cell infiltration, such as naïve B cells, neutrophils, and eosinophils, and there was a difference in the TME between the high VM score group and the low VM score group. LUAD patients in the high VM score group were more sensitive to antitumor drugs. Conclusion: In summary, the VM score developed in this study is a valuable indicator for evaluating the prognosis and immune landscape of LUAD patients. VM may be a potential target for antitumor therapy in lung cancer.

VE-Cadherin in Cancer-Associated Angiogenesis: A Deceptive Strategy of Blood Vessel Formation

Tumor growth depends on the vascular system, either through the expansion of blood vessels or novel adaptation by tumor cells. One of these novel pathways is vasculogenic mimicry (VM), which is defined as a tumor-provided vascular system apart from endothelial cell-lined vessels, and its origin is partly unknown. It involves highly aggressive tumor cells expressing endothelial cell markers that line the tumor irrigation. VM has been correlated with high tumor grade, cancer cell invasion, cancer cell metastasis, and reduced survival of cancer patients. In this review, we summarize the most relevant studies in the field of angiogenesis and cover the various aspects and functionality of aberrant angiogenesis by tumor cells. We also discuss the intracellular signaling mechanisms involved in the abnormal presence of VE-cadherin (CDH5) and its role in VM formation. Finally, we present the implications for the paradigm of tumor angiogenesis and how targeted therapy and individualized studies can be applied in scientific analysis and clinical settings.

Molecular vasculogenic mimicry-Related signatures predict clinical outcomes and therapeutic responses in bladder cancer: Results from real-world cohorts

Bladder cancer (BLCA) is a heterogeneous disease, and there are many classical molecular subtypes that reflect tumor immune microenvironment (TME) heterogeneity but their clinical utility is limited and correct individual treatment and prognosis cannot be predicted based on them. To find reliable and effective biomarkers and tools for predicting patients' clinical responses to several therapies, we developed a new systemic indicator of molecular vasculogenic mimicry (VM)-related genes mediated by molecular subtypes based on the Xiangya cohort and additional external BLCA cohorts using a random forest algorithm. A correlation was then done between the VM_Score and classical molecular subtypes, clinical outcomes, immunophenotypes, and treatment options for BLCA. With the VM_Score, it is possible to predict classical molecular subtypes, immunophenotypes, prognosis, and therapeutic potential of BLCA with high accuracy. The VM_Scores of high levels indicate a more anticancer immune response but a worse prognosis due to a more basal and inflammatory phenotype. The VM_Score was also found associated with low sensitivity to antiangiogenic and targeted therapies targeting the FGFR3, β-catenin, and PPAR-γ pathways but with high sensitivity to cancer immunotherapy, neoadjuvant chemotherapy, and radiotherapy. A number of aspects of BLCA biology were reflected in the VM_Score, providing new insights into precision medicine. Additionally, the VM_Score may be used as an indicator of pan-cancer immunotherapy response and prognosis.

ANGPTL4 functions as an oncogene through regulation of the ETV5/CDH5/AKT/MMP9 axis to promote angiogenesis in ovarian cancer

BACKGROUND

Angiopoietin-like 4 (ANGPTL4) is highly expressed in a variety of neoplasms and promotes cancer progression. Nevertheless, the mechanism of ANGPTL4 in ovarian cancer (OC) metastasis remains unclear. This study aimeds to explore whether ANGPTL4 regulates OC progression and elucidate the underlying mechanism.

METHODS

ANGPTL4 expression in clinical patient tumor samples was determined by immunohistochemistry (IHC) and high-throughput sequencing. ANGPTL4 knockdown (KD) and the addition of exogeneous cANGPTL4 protein were used to investigate its function. An in vivo xenograft tumor experiment was performed by intraperitoneal injection of SKOV3 cells transfected with short hairpin RNAs (shRNAs) targeting ANGPTL4 in nude mice. Western blotting and qRT-PCR were used to detect the levels of ANGPTL4, CDH5, p-AKT, AKT, ETV5, MMP2 and MMP9 in SKOV3 and HO8910 cells transfected with sh-ANGPTL4 or shRNAs targeting ETV5.

RESULTS

Increased levels of ANGPTL4 were associated with poor prognosis and metastasis in OC and induced the angiogenesis and metastasis of OC cells both in vivo and in vitro. This tumorigenic effect was dependent on CDH5, and the expression levels of ANGPTL4 and CDH5 in human OC werepositively correlated. In addition, CDH5 activated p-AKT, and upregulated the expression of MMP2 and MMP9. We also found that the expression of ETV5 was upregulated by ANGPTL4, which could bind the promoter region of CDH5, leading to increased CDH5 expression.

CONCLUSION

Our data indicated that an increase in the ANGPTL4 level results in increased ETV5 expression in OC, leading to metastasis via activation of the CDH5/AKT/MMP9 signaling pathway.

A vasculogenic mimicry prognostic signature associated with immune signature in human gastric cancer

BACKGROUND

Gastric cancer (GC) is one of the most lethal malignant tumors worldwide with poor outcomes. Vascular mimicry (VM) is an alternative blood supply to tumors that is independent of endothelial cells or angiogenesis. Previous studies have shown that VM was associated with poor prognosis in patients with GC, but the underlying mechanisms and the relationship between VM and immune infiltration of GC have not been well studied.

METHODS

In this study, expression profiles from VM-related genes were retrieved from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Cox regression was performed to identify key VM-related genes for survival. Subsequently, a novel risk score model in GC named VM index and a nomogram was constructed. In addition, the expression of one key VM-related gene (serpin family F member 1, SERPINF1) was validated in 33 GC tissues and 23 paracancer tissues using immunohistochemistry staining.

RESULTS

Univariate and multivariate Cox regression suggested that SERPINF1 and tissue factor pathway inhibitor 2 (TFPI2) were independent risk factors for the prognosis of patients with GC. The AUC (> 0.7) indicated the satisfactory discriminative ability of the nomogram. SsGESA and ESTIMATE showed that higher expression of SERPINF1 and TFPI2 is associated with immune infiltration of GC. Immunohistochemistry staining confirmed that the expression of SERPINF1 protein was significantly higher in GC tissues than that in paracancer tissues.

CONCLUSION

A VM index and a nomogram were constructed and showed satisfactory predictive performance. In addition, VM was confirmed to be widely involved in immune infiltration, suggesting that VM could be a promising target in guiding immunotherapy. Taken together, we identified SERPINF1 and TFPI2 as immunologic and prognostic biomarkers related to VM in GC.

Resveratrol suppresses serum-induced vasculogenic mimicry through impairing the EphA2/twist-VE-cadherin/AKT pathway in human prostate cancer PC-3 cells

Vasculogenic mimicry (VM) is closely related to cancer progression and metastasis, contributing to poor prognosis in patients with cancer. Resveratrol (RES) is well known to possess anti-cancer activity. This study explored the new role of RES in VM incidence in human prostate cancer (PCa) PC-3 cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, transwell invasion, and three-dimensional culture VM tube formation assays were performed to check the cell viability, invasive ability, and vessel-like networks formation, respectively. VM-related proteins were detected by Western blots. The activity of metalloproteinase-2 (MMP-2) was identified by gelatin zymography. Vascular endothelial cadherin (VE-cadherin) mRNA was assessed by reverse transcriptase-polymerase chain reaction. Nuclear twist expression was observed by immunofluorescence assay. RES reduced serum-induced invasion and VM formation. Serum-induced phosphorylation of erythropoiethin-producing hepatoceullular A2 (EphA2) and the expression of VE-cadherin at the protein and mRNA levels were decreased after RES treatment. RES inhibited serum-induced expression and nuclear localization of twist. Serum-activated AKT signaling pathway, including MMP-2 and laminin subunit 5 gamma-2, was impaired by RES. These results suggested that RES may have an anti-VM effect through suppressing the EphA2/twist-VE-cadherin/AKT signaling cascade in PCa PC-3 cells.

Interference in melanoma CD248 function reduces vascular mimicry and metastasis

Background

Tumor vascular mimicry is an emerging issue that affects patient survival while having no treatment at the current moment. Despite several factors implicated in vascular mimicry, little is known about stromal factors that modulate tumor microenvironment and shape malignant transformation. CD248, a type-I transmembrane protein dominantly expressed in stromal cells, mediates the interaction between cells and extracellular matrix proteins. CD248 protein expression is associated with the metastatic melanoma phenotype and promotes tumor progression in the stromal cells. This study aimed to explore the cell-autonomous effects of CD248 in melanoma vascular mimicry to aid cancer therapy development.

Methods

Loss-of-function approaches in B16F10 melanoma cells were used to study the cell-autonomous effects of CD248 on cell adhesion, migration, proliferation, and vascular mimicry. A solid-phase binding assay was performed to identify the interaction between CD248 and fibronectin. Horizontal and vertical cell migration assays were performed to analyze cell migration activity, and cell-patterned network formation on Matrigel was used to evaluate vascular mimicry activity. Recombinant CD248 (rCD248) proteins were generated, and whether rCD248 interfered with melanoma CD248 functions was evaluated in vitro. An experimental lung metastasis mouse model was used to investigate the effect of rCD248 treatment in vivo.

Results

CD248 protein expression in melanoma cells was increased by a fibroblast-conditioned medium. Knockdown of CD248 expression significantly decreased cell adhesion to fibronectin, cell migration, and vascular mimicry in melanoma cells. The lectin domain of CD248 was directly involved in the interaction between CD248 and fibronectin. Furthermore, rCD248 proteins containing its lectin domain inhibited cell adhesion to fibronectin and slowed down cell migration and vascular mimicry. Treatment with rCD248 protein could reduce pulmonary tumor burden, accompanied by a reduction in vascular mimicry in mice with melanoma lung metastasis.

Conclusion

CD248 expression in melanoma cells promotes malignant transformation by increasing the activity of cell adhesion, migration, and vascular mimicry, whereas rCD248 protein functions as a molecular decoy interfering with tumor-promoting effects of CD248 in melanoma cells.

N6-methyladenosine-modified HOTAIRM1 promotes vasculogenic mimicry formation in glioma

Vasculogenic mimicry (VM) has been reported to accelerate angiogenesis in malignant tumors, yet the mechanism underlying VM has not been fully elucidated. N6-methyladenosine (m6A) mainly modulates mRNA fate and affects multiple tumorigenesis. Here, we aimed to investigate m6A-modified HOXA transcript antisense RNA myeloid-specific 1 (HOTAIRM1) in the regulation of glioma-associated VM formation. Gene expression was analyzed by quantitative RT-PCR. Cell viability, metastases, and VM formation capacity were determined by CCK-8, migration and invasion, as well as tube formation assays, respectively. The function and mechanisms of m6A-modified HOTAIRM1 were defined through liquid chromatography-tandem mass spectrometry m6A quantification, methylated RNA immunoprecipitation sequencing, RNA stability assays, and RNA pull-down experiments. A glioma xenograft mouse model was further established for VM evaluation in vivo. The results showed that HOTAIRM1, methyltransferase-like 3 (METTL3), and insulin-like growth factor binding protein 2 (IGFBP2) were upregulated in glioma tissues and cell lines. HOTAIRM1 functions as an oncogene in glioma progression; however, knockdown of HOTAIRM1 significantly reduced cell viability, migration, invasion, and VM formation. Notably, METTL3-dependent m6A modification enhanced HOTAIRM1 mRNA stability, whereas knockdown of METTL3 deficiency significantly suppressed VM in glioma. Moreover, HOTAIRM1 was found to bind IGFBP2, and HOTAIRM1 deficiency blocked glioma progression and VM formation in vivo. Our results indicated that METTL3-dependent m6A-modified HOTAIRM1 promoted VM formation in glioma.

Immunotherapy checkpoints in ovarian cancer vasculogenic mimicry: Tumor immune microenvironments, and drugs

Vasculogenic mimicry (VM), a vessel-like structure independent of endothelial cells, commonly exists in solid tumors which requires blood vessels to grow. As a special source of blood supply for tumor progression to a more aggressive state, VM has been observed in a variety of human malignant tumors and is tightly associated with tumor proliferation, invasion, metastasis, and poor patient prognosis. So far, various factors, including immune cells and cytokines, were reported to regulate ovarian cancer progression by influencing VM formation. Herein, we review the mechanisms that regulate VM formation in ovarian cancer and the effect of cells, cytokines, and signaling molecules in the tumor microenvironment on VM formation, Furthermore, we summarize the current clinical application of drugs targeting VM formation.

TAZ promotes vasculogenic mimicry in gastric cancer through the upregulation of TEAD4

BACKGROUND AND AIM

Vasculogenic mimicry (VM) is a unique blood supply pattern in malignant tumors that is closely associated with metastasis and poor prognosis. The Hippo signaling effector TAZ is upregulated in several cancers, promoting cancer proliferation and metastasis. This study aimed to identify the function of TAZ and its regulatory mechanism in promoting VM in gastric cancer (GC).

METHODS

The expression of TAZ and TEAD4 and their correlations with overall survival and VM-related markers were analyzed in 228 cases of GC. The regulatory mechanism of TAZ and its interaction with TEAD4 in epithelial-mesenchymal transition (EMT) and VM were investigated in vitro and in vivo.

RESULTS

TAZ was highly expressed in GC samples and was associated with shorter patient survival time. TAZ expression was positively correlated with TEAD4 and VM in patients with GC. TAZ enhanced the migration and invasion capacity of GC cells through EMT in vitro and upregulated the expression of VM-associated proteins, including VE-cadherin, MMP2, and MMP9, thus promoting VM formation. Overexpression of TAZ accelerated the growth of subcutaneous xenograft and promoted VM formation in vivo. Co-immunoprecipitation assays showed that TAZ can directly bind to TEAD4, and in vitro experiments showed that this binding mediates the function of TAZ in regulating EMT and VM formation in GC.

CONCLUSIONS

TAZ promotes GC metastasis and VM by upregulating TEAD4 expression. Our findings expand the role of TAZ in VM and provide new theoretical support for the use of antiangiogenic therapy in the treatment of advanced GC.

Correlation Between Contrast-Enhanced Ultrasound and Immune Response of Distant Hepatocellular Carcinoma After Radiofrequency Ablation in a Murine Model

OBJECTIVES

To investigate the relationships between contrast-enhanced ultrasound (CEUS) and the immune status of a distant tumor after radiofrequency ablation (RFA) in a mouse model of hepatocellular carcinoma (HCC).

METHODS

Twenty-four mice with two liver tumors were randomized into two groups. RFA was performed on the left tumor in the RFA group. Growth of the right tumors in both groups was monitored after RFA. According to tumor growth, two time points at which tumor growth was halted and restored were selected for study. Then, another 24 mice were randomized into RFA and non-RFA groups. The CEUS parameters, apoptosis, CD8+ T cell, and vasculogenic mimicry (VM) of the right tumors were analyzed on the two aforementioned time points in each group.

RESULTS

Days 3 and 6 were selected as the time points of tumor retardation and progressive growth, respectively. The different immune status of the distant tumors at the two time points after RFA was confirmed by CD8+ T cell and apoptosis (both P < 0.001). Peak intensity, time to peak, area wash-in, and area wash-out of the CEUS parameters increased significantly in the day-6 RFA group versus the day-3 RFA group (P < .001, P = .017, P = .005, P = .002, respectively). VM of the day-6 RFA group was higher than that of the day-3 RFA group (P = .003).

CONCLUSIONS

CEUS maybe a good method to follow the immune response after RFA in an advanced HCC mouse model.

Orchestrated expression of vasculogenic mimicry and laminin-5γ2 is an independent prognostic marker in oral squamous cell carcinoma

Vasculogenic mimicry (VM), an endothelial cell-independent alternative mechanism of blood supply to the malignant tumour, has long been considered as an adverse prognostic factor in many cancers. The correlation of VM with laminin-5γ2 and the assessment of their harmonized expression as an independent risk factor have not been elucidated yet in oral squamous cell carcinoma (OSCC). CD31/PAS staining stratified 116 clinically diagnosed OSCC specimens into VM+ and VM- cohorts. The expression pattern of laminin-5γ2 and its upstream modulator MMP2 was evaluated by immunohistochemistry and Western blot. The Kaplan-Meier and Cox regression analyses were performed to assess the survival and prognostic implications. The presence of VM demonstrated a significant correlation with the expression of laminin-5γ2 (p < .001) and MMP2 (p < .001). This pattern was mirrored by the significant upregulation of laminin-5γ2 and MMP2 in VM+ cohorts compared with the VM- ones. Furthermore, co-expression of VM and laminin-5γ2 was significantly associated with tumour grade (p = .010), primary tumour size (p < .001), lymph node metastasis (p = .001) and TNM stages (p < .001) but not with patients' age, gender, tobacco and alcohol consumption habit. Vasculogenic mimicry and laminin-5γ2 double-positive cohort displayed a significantly poorer disease-free survival (DFS) and overall survival (OS). Vasculogenic mimicry, laminin-5γ2 and their subsequent dual expression underlie a significant prognostic value for DFS [hazard ratio (HR) = 9.896, p = .028] and OS [HR = 21.401, p = .033] in OSCC patients. Together, our findings imply that VM along with laminin-5γ2 is strongly linked to the malignant progression in OSCC and VM and laminin-5γ2 coordination emerges as a critical prognostic biomarker for OSCC.

Sp1 Plays a Key Role in Vasculogenic Mimicry of Human Prostate Cancer Cells

Sp1 transcription factor regulates genes involved in various phenomena of tumor progression. Vasculogenic mimicry (VM) is the alternative neovascularization by aggressive tumor cells. However, there is no evidence of the relationship between Sp1 and VM. This study investigated whether and how Sp1 plays a crucial role in the process of VM in human prostate cancer (PCa) cell lines, PC-3 and DU145. A cell viability assay and three-dimensional culture VM tube formation assay were performed. Protein and mRNA expression levels were detected by Western blot and reverse transcriptase-polymerase chain reaction, respectively. The nuclear twist expression was observed by immunofluorescence assay. A co-immunoprecipitation assay was performed. Mithramycin A (MiA) and Sp1 siRNA significantly decreased serum-induced VM, whereas Sp1 overexpression caused a significant induction of VM. Serum-upregulated vascular endothelial cadherin (VE-cadherin) protein and mRNA expression levels were decreased after MiA treatment or Sp1 silencing. The protein expression and the nuclear localization of twist were increased by serum, which was effectively inhibited after MiA treatment or Sp1 silencing. The interaction between Sp1 and twist was reduced by MiA. On the contrary, Sp1 overexpression enhanced VE-cadherin and twist expressions. Serum phosphorylated AKT and raised matrix metalloproteinase-2 (MMP-2) and laminin subunit 5 gamma-2 (LAMC2) expressions. MiA or Sp1 silencing impaired these effects. However, Sp1 overexpression upregulated phosphor-AKT, MMP-2 and LAMC2 expressions. Serum-upregulated Sp1 was significantly reduced by an AKT inhibitor, wortmannin. These results demonstrate that Sp1 mediates VM formation through interacting with the twist/VE-cadherin/AKT pathway in human PCa cells.

Sunitinib increases the cancer stem cells and vasculogenic mimicry formation via modulating the lncRNA-ECVSR/ERβ/Hif2-α signaling

Sunitinib is the first-line drug for treating renal cell carcinoma (RCC), and it functions mainly through inhibition of tumor angiogenesis. However, the patients may become insensitive or develop resistance toward sunitinib treatment, but the underlying mechanisms have not yet been fully elucidated. Herein, it was found that sunitinib could have adverse effects of promoting RCC progression by increasing vascular mimicry (VM) formation of RCC cells. Mechanism dissection revealed that sunitinib can increase the expression of a long non-coding RNA (lncRNA), lncRNA-ECVSR, thereby enhancing the stability of estrogen receptor β (ERβ) mRNA. Subsequently, the increased ERβ expression can then function via transcriptional up-regulation of Hif2-α. Notably, sunitinib-increased lncRNA-ECVSR/ERβ/Hif2-α signaling resulted in an increased cancer stem cell (CSC) phenotype, thereby promoting VM formation. Furthermore, the sunitinib/lncRNA-ECVSR-increased ERβ expression can transcriptionally regulate lncRNA-ECVSR expression via a positive-feedback loop. Supportively, preclinical studies using RCC mouse xenografts demonstrated that combining sunitinib with the small molecule anti-estrogen PHTPP can increase sunitinib efficacy with reduced VM formation. Collectively, the findings of this study may aid in the development of potential biomarker(s) and novel therapies to better monitor and suppress RCC progression.

Identification of Vasculogenic Mimicry in Histological Samples

Vasculogenic mimicry has been identified in several malignancies and is generally associated with aggressive tumor growth and increased risk of metastasis. Patterned matrix can be identified in light microscopy of tumor sections stained with periodic acid-Schiff (PAS) without hematoxylin counterstain. In this chapter, the process is comprehensively described including tissue sources, formalin fixation and paraffin embedding, staining protocols, and the method for pattern identification in the microscope. Specific pattern types are illustrated in figures, and a number of pitfalls are detailed. The text can be used as a guideline by any researcher or clinician that wishes to evaluate histological samples for the presence of vasculogenic mimicry.

A Three-Dimensional Culture-Based Assay to Detect Early Stages of Vasculogenic Mimicry in Ovarian Cancer Cells

Vasculogenic mimicry is a cellular mechanism in which tumor cells grow and align forming complex three-dimensional (3D) channel-like structures in a hypoxic microenvironment. This phenomenon represents a novel oxygen, nutrient, and blood supply, in a similar way as occurs in classic angiogenesis. Vasculogenic mimicry has been described in numerous clinical tumors including breast, prostate, lung, and ovarian cancers where it is associated with poor prognosis; thus, it is considered as a hallmark of highly aggressive and metastatic tumors. Here, we describe a simple method to model the in vitro formation of three-dimensional cellular networks over Matrigel in SKOV3 ovarian cancer cells representing the early stages of vasculogenic mimicry.

Immunohistochemistry for VM Markers

Vasculogenic mimicry (VM) is the biological process by which aggressive cancer cells are able to organize themselves-independently from endothelial cells-into new vessel-like structures to sustain fast tumor perfusion and thus an efficient supply of oxygen and nutrients, required for rapid cancer growth and dissemination. In the last two decades, the molecular mechanisms and key regulators of VM have been identified. Several methods are currently available to detect VM both in vitro and in vivo, but the gold standard is still the immunohistochemical staining of specific antigens. Even though many markers are debated if belong to the angiogenic process or VM exclusively, the immunohistochemistry of CD31 and the PAS reaction often clarify in frozen or paraffin sections the pathologic status and the vasculature grade of a tumor mass.

MicroRNA-204/CREB5 axis regulates vasculogenic mimicry in breast cancer cells

BACKGROUND

Vasculogenic mimicry (VM) is characterized by formation of three-dimensional (3D) channels-like structures by tumor cells, supplying the nutrients needed for tumor growth. VM is stimulated by hypoxic tumor microenvironment, and it has been associated with increased metastasis and clinical poor outcome in cancer patients. cAMP responsive element (CRE)-binding protein 5 (CREB5) is a hypoxia-activated transcription factor involved in tumorigenesis. However, CREB5 functions in VM and if its regulated by microRNAs remains unknown in breast cancer.

OBJECTIVE

We aim to study the functional relationships between VM, CREB5 and microRNA-204-5p (miR-204) in breast cancer cells.

METHODS

CREB5 expression was evaluated by mining the public databases, and using RT-qPCR and Western blot assays. CREB5 expression was silenced using short-hairpin RNAs in MDA-MB-231 and MCF-7 breast cancer cells. VM formation was analyzed using matrigel-based cultures in hypoxic conditions. MiR-204 expression was restored in cancer cells by transfection of RNA mimics. Luciferase reporter assays were performed to evaluate the binding of miR-204 to 3'UTR of CREB5.

RESULTS

Our data showed that CREB5 mRNA expression was upregulated in a set of breast cancer cell lines and clinical tumors, and it was positively associated with poor prognosis in lymph nodes positive and grade 3 basal breast cancer patients. Silencing of CREB5 impaired the hypoxia-induced formation of 3D channels-like structures representative of the early stages of VM in MDA-MB-231 cells. In contrast, VM formation was not observed in MCF-7 cells. Interestingly, we found that CREB5 expression was negatively regulated by miR-204 mimics in breast cancer cells. Functional analysis confirmed that miR-204 binds to CREB5 3'-UTR indicating that it's an ulterior effector.

CONCLUSIONS

Our findings suggested that CREB5 could be a potential biomarker of disease progression in basal subtype of breast cancer, and that perturbations of the miR-204/CREB5 axis plays an important role in VM development in breast cancer cells.

Methionine aminopeptidase‑2 is a pivotal regulator of vasculogenic mimicry

Vasculogenic mimicry (VM) is the formation of a blood supply system that confers aggressive and metastatic properties to tumors and correlates with a poor prognosis in cancer patients. Thus, the inhibition of VM is considered an effective approach for cancer treatment, although such a mechanism remains poorly described. In the present study, we examined methionine aminopeptidase-2 (MetAP2), a key factor of angiogenesis, and demonstrated that it is pivotal for VM, using pharmacological and genetic approaches. Fumagillin and TNP-470, angiogenesis inhibitors that target MetAP2, significantly suppressed VM in various human cancer cell lines. We established MetAP2-knockout (KO) human fibrosarcoma HT1080 cells using the CRISPR/Cas9 system and found that VM was attenuated in these cells. Furthermore, re-expression of wild-type MetAP2 restored VM in the MetAP2-KO HT1080 cells, but the substitution of D251, a conserved amino acid in MetAP2, failed to rescue the VM. Collectively, our results demonstrate that MetAP2 is critical for VM in human cancer cells and suggest fumagillin and TNP-470 as potent VM-suppressing agents.

Propensity for Early Metastatic Spread in Breast Cancer: Role of Tumor Vascularization Features and Tumor Immune Infiltrate

Breast cancer is a complex and highly heterogeneous disease consisting of various subtypes. It is classified into human epidermal growth receptor 2 (HER-2)-enriched, luminal A, luminal B and basal-like/triple negative (TNBC) breast cancer, based on histological and molecular features. At present, clinical decision-making in breast cancer is focused only on the assessment of tumor cells; nevertheless, it has been recognized that the tumor microenvironment (TME) plays a critical biologic role in breast cancer. This is constituted by a large group of immune and non-immune cells, but also by non-cellular components, such as several cytokines. TME is deeply involved in angiogenesis, immune-evasion strategies, and propensity for early metastatic spread, impacting on prognosis and prediction of response to specific treatments. In this review, we focused our attention on the early morphological changes of tumor microenvironment (tumor vasculature features, presence of immune and non-immune cells infiltrating the stroma, levels of cytokines) during breast cancer development. At the same time, we correlate these characteristics with early metastatic propensity (defined as synchronous metastasis or early recurrence) with particular attention to breast cancer subtypes.

Microbial metabolite deoxycholic acid promotes vasculogenic mimicry formation in intestinal carcinogenesis

A high-fat diet (HFD) leads to long-term exposure to gut microbial metabolite secondary bile acids, such as deoxycholic acid (DCA), in the intestine, which is closely linked to colorectal cancer (CRC). Evidence reveals that vasculogenic mimicry (VM) is a critical event for the malignant transformation of cancer. Therefore, this study investigated the crucial roles of DCA in the regulation of VM and the progression of intestinal carcinogenesis. The effects of an HFD on VM formation and epithelial-mesenchymal transition (EMT) in human CRC tissues were investigated. The fecal DCA level was detected in HFD-treated Apc^min/+ mice. Then the effects of DCA on VM formation, EMT, and vascular endothelial growth factor receptor 2 (VEGFR2) signaling were evaluated in vitro and in vivo. Here we demonstrated that compared with a normal diet, an HFD exacerbated VM formation and EMT in CRC patients. An HFD could alter the composition of the gut microbiota and significantly increase the fecal DCA level in Apc^min/+ mice. More importantly, DCA promoted tumor cell proliferation, induced EMT, increased VM formation, and activated VEGFR2, which led to intestinal carcinogenesis. In addition, DCA enhanced the proliferation and migration of HCT-116 cells, and induced EMT process and vitro tube formation. Furthermore, the silence of VEGFR2 reduced DCA-induced EMT, VM formation, and migration. Collectively, our results indicated that microbial metabolite DCA promoted VM formation and EMT through VEGFR2 activation, which further exacerbated intestinal carcinogenesis.

Vasculogenic mimicry correlates to presenting symptoms and mortality in uveal melanoma

PURPOSE

Fluid-conducting extracellular matrix patterns known as vasculogenic mimicry (VM) have been associated with poor prognosis in uveal melanoma and other cancers. We investigate the correlations between VM, presenting symptoms, mortality, and the area density of periodic acid-Schiff positive histological patterns (PAS density).

METHODS

Sixty-nine patients that underwent enucleation for uveal melanoma between 2000 and 2007 were included. Clinicopathological parameters presenting symptoms and outcomes were collected. Histological tumor sections were evaluated for VM and PAS density was quantified with digital image analysis.

RESULTS

Thirty-four patients (49%) presented with blurred vision. 18 (26%) with a shadow in the visual field, 7 (10%) with photopsia and/or floaters, and 2 (3%) with metamorphopsia. Nine patients (13%) had no symptoms at all. Median follow-up was 16.7 years (SD 2.6). A shadow in the visual field, but no other symptom, was positively correlated with the presence of VM (φ 0.70, p < 0.001) and greater PAS density (p < 0.001). In multivariate regression, retinal detachment (RD), presence of VM, and PAS density ≥ median were independent predictors of a shadow, but not tumor distance to the macula, tumor apical thickness, tumor diameter, or ciliary body engagement. The presence of VM was associated with significantly shorter cumulative disease-specific survival (Wilcoxon p = 0.04), but not PAS density ≥ median, presenting symptoms or RD (p > 0.28).

CONCLUSION

Tumors from uveal melanoma patients that report a visual field shadow are likely to display VM and greater PAS density, likely explaining the previously reported association between this symptom and poor prognosis.

Normalization of the tumor microvasculature based on targeting and modulation of the tumor microenvironment

Angiogenesis is an essential process for tumor development. Owing to the imbalance between pro- and anti-angiogenic factors, the tumor vasculature possesses the characteristics of tortuous, hyperpermeable vessels and compressive force, resulting in a reduction in the effect of traditional chemotherapy and radiotherapy. Anti-angiogenesis has emerged as a promising strategy for cancer treatment. Tumor angiogenesis, however, has been proved to be a complex process in which the tumor microenvironment (TME) plays a vital role in the initiation and development of the tumor microvasculature. The host stromal cells in the TME, such as cancer associated fibroblasts (CAFs), tumor associated macrophages (TAMs) and Treg cells, contribute to angiogenesis. Furthermore, the abnormal metabolic environment, such as hypoxia and acidosis, leads to the up-regulated expression of angiogenic factors. Indeed, normalization of the tumor microvasculature via targeting and modulating the TME has become a promising strategy for anti-angiogenesis and anti-tumor therapy. In this review, we summarize the abnormalities of the tumor microvasculature, tumor angiogenesis induced by an abnormal metabolic environment and host stromal cells, as well as drug delivery therapies to restore the balance between pro- and anti-angiogenic factors by targeting and normalizing the tumor vasculature in the TME.

Crocetin suppresses angiogenesis and metastasis through inhibiting sonic hedgehog signaling pathway in gastric cancer

Gastric cancer (GC) is one of the major causes of cancer-related deaths and chemoresistance is a key obstacle to the treatment of GC, particularly in advanced GC. As an active component of saffron stigma, crocetin has important therapeutic effects on various diseases including tumors. However, the therapeutic potential of crocetin targeting GC is still unclear and the underlying mechanisms are remained to be further explored. In this study, crocetin significantly inhibited angiogenesis in GC, including tubes of HUVECs and vasculogenic mimicry (VM) formation of GC cells. Crocetin also suppressed cell proliferation, migration and invasion. To explore which signaling pathway involving in crocetin, HIF-1α, Notch1, Sonic hedgehog (SHH) and VEGF were examined with crocetin treatment and we found that SHH significantly decreased. Crocetin suppressed SHH signaling with SHH, PTCH2, Sufu and Gli1 protein level decreased in western blot assay. In addition, crocetin suppressed SHH secretion in GC and HUVEC cells. The promoted effects on cell migration induced by secreted SHH were also inhibited by crocetin in GC and HUVEC cell co-culture system. Furthermore, recombinant SHH promoted angiogenesis as well as cell migration and proliferation. However, these promoted effects were reversed by crocetin treatment. These results revealed that crocetin suppressed GC angiogenesis and metastasis through SHH signaling pathway, indicating that crocetin may function as an effective therapeutic drug against GC.

New Peptide-Drug Conjugates for Precise Targeting of SORT1-Mediated Vasculogenic Mimicry in the Tumor Microenvironment of TNBC-Derived MDA-MB-231 Breast and Ovarian ES-2 Clear Cell Carcinoma Cells

Vasculogenic mimicry (VM) is defined as the formation of microvascular channels by genetically deregulated cancer cells and is often associated with high tumor grade and cancer therapy resistance. This microcirculation system, independent of endothelial cells, provides oxygen and nutrients to tumors, and contributes also in part to metastasis. VM has been observed in ovarian cancer and in triple negative breast cancer (TNBC) and shown to correlate with decreased overall cancer patient survival. Thus, strategies designed to inhibit VM may improve cancer patient treatments. In this study, sortilin (SORT1) receptor was detected in in vitro 3D capillary-like structures formed by ES-2 ovarian cancer and MDA-MB-231 TNBC-derived cells when grown on Matrigel. SORT1 gene silencing or antibodies directed against its extracellular domain inhibited capillary-like structure formation. In vitro, VM also correlated with increased gene expression of matrix metalloproteinase-9 (MMP-9) and of the cancer stem cell marker CD133. In vivo ES-2 xenograft model showed PAS+/CD31- VM structures (staining positive for both SORT1 and CD133). TH1904, a Doxorubicin-peptide conjugate that is internalized by SORT1, significantly decreased in vitro VM at low nM concentrations. In contrast, VM was unaffected by unconjugated Doxorubicin or Doxil (liposomal Doxorubicin) up to μM concentrations. TH1902, a Docetaxel-peptide conjugate, altered even more efficiently in vitro VM at pM concentrations. Overall, current data evidence for the first time that 1) SORT1 itself exerts a crucial role in both ES-2 and MDA-MB-231 VM, and that 2) VM in these cancer cell models can be efficiently inhibited by the peptide-drug conjugates TH1902/TH1904. These new findings also indicate that both peptide-drug conjugates, in addition to their reported cytotoxicity, could possibly inhibit VM in SORT1-positive TNBC and ovarian cancer patients.

Crosstalks Among Cancer Stem Cells and Histopathologic Features in Determining Prognosis in Canine Mammary Gland Carcinomas

The purpose of the present work was the evaluation of the prognostic potential of histopathologic features, cancer stem cells (CSCs), and epthelial-mesenchymal transition (EMT) in relation to lymph node status and lymphovascular invasion (LVI) in canine mammary gland carcinomas (CMGCs). CSCs are proposed as the main cause of tumorigenesis, therapy failure, and recurrence which form a small fraction of tumor bulk. We evaluated presence of micropapillary growth pattern (MGP), infiltration into surrounding tissues (IST), and vasculogenic mimicry (VM) in H&E stained slides of 26 paraffin-embedded tumor samples. Lymph nodes of all cases were assessed. Additionally, they were examined immunohistochemically in terms of vimentin expression as an indicator of EMT which is a well-known mechanism for metastasis, and CD44, CD24, and ALDH1 for CSCs detection. Data analyses showed significant relationships between MGP and CSCs (P = 0.037), VM and CSCs (P = 0.013), lymph node status and CSCs (P = 0.0001), lymph node status and EMT (P = 0.003), IST and LVI (P = 0.05), VM and LVI (P = 0.01), VM and lymph node status (P = 0.007), and LVI and lymph node status (P = 0.04). Results indicated the prognostic value of MGP, VM, and CSCs with respect to confirmed prognostic markers, including LVI and lymph node involvement, in CMGCs.

uPAR controls vasculogenic mimicry ability expressed by drug-resistant melanoma cells

Malignant melanoma is a highly aggressive skin cancer characterized by an elevated grade of tumor cell plasticity. Such plasticity allows melanoma cells adaptation to different hostile conditions and guarantees tumor survival and disease progression, including aggressive features such as drug resistance. Indeed, almost 50% of melanoma rapidly develop resistance to the BRAFV600E inhibitor vemurafenib, with fast tumor dissemination, a devastating consequence for patients' outcomes. Vasculogenic mimicry (VM), the ability of cancer cells to organize themselves in perfused vascular-like channels, might sustain tumor spread by providing vemurafenib-resistant cancer cells with supplementary ways to enter into circulation and disseminate. Thus, this research aims to determine if vemurafenib resistance goes with the acquisition of VM ability by aggressive melanoma cells, and identify a driving molecule for both vemurafenib resistance and VM. We used two independent experimental models of drug-resistant melanoma cells, the first one represented by a chronic adaptation of melanoma cells to extracellular acidosis, known to drive a particularly aggressive and vemurafenib-resistant phenotype, the second one generated with chronic vemurafenib exposure. By performing in vitro tube formation assay and evaluating the expression levels of the VM markers EphA2 and VE-cadherin by western blotting and flow cytometer analyses, we demonstrated that vemurafenib-resistant cells obtained by both models are characterized by an increased ability to perform VM. Moreover, by exploiting the CRISPR-Cas9 technique and using the urokinase plasminogen activator receptor (uPAR) inhibitor M25, we identified uPAR as a driver of VM expressed by vemurafenib-resistant melanoma cells. Thus, uPAR targeting may be successfully leveraged as a new complementary therapy to inhibit VM in drug-resistant melanoma patients, to counteract the rapid progression and dissemination of the disease.

CD36 promotes vasculogenic mimicry in melanoma by mediating adhesion to the extracellular matrix

Background

The formation of blood vessels within solid tumors directly contributes to cancer growth and metastasis. Until recently, tumor vasculature was thought to occur exclusively via endothelial cell (EC) lined structures (i.e. angiogenesis), but a second source of tumor vasculature arises from the cancer cells themselves, a process known as vasculogenic mimicry (VM). While it is generally understood that the function of VM vessels is the same as that of EC-lined vessels (i.e. to supply oxygen and nutrients to the proliferating cancer cells), the molecular mechanisms underpinning VM are yet to be fully elucidated.

Methods

Human VM-competent melanoma cell lines were examined for their VM potential using the in vitro angiogenesis assays (Matrigel), together with inhibition studies using small interfering RNA and blocking monoclonal antibodies. Invasion assays and adhesion assays were used to examine cancer cell function.

Results

Herein we demonstrate that CD36, a cell surface glycoprotein known to promote angiogenesis by ECs, also supports VM formation by human melanoma cancer cells. In silico analysis of CD36 expression within the melanoma cohort of The Cancer Genome Atlas suggests that melanoma patients with high expression of CD36 have a poorer clinical outcome. Using in vitro ‘angiogenesis’ assays and CD36-knockdown approaches, we reveal that CD36 supports VM formation by human melanoma cells as well as adhesion to, and invasion through, a cancer derived extracellular matrix substrate. Interestingly, thrombospondin-1 (TSP-1), a ligand for CD36 on ECs that inhibits angiogenesis, has no effect on VM formation. Further investigation revealed a role for laminin, but not collagen or fibronectin, as ligands for CD36 expressing melanoma cells.

Conclusions

Taken together, this study suggests that CD36 is a novel regulator of VM by melanoma cancer cells that is facilitated, at least in part, via integrin-α₃ and laminin. Unlike angiogenesis, VM is not perturbed by the presence of TSP-1, thus providing new information on differences between these two processes of tumor vascularization which may be exploited to combat cancer progression.

Tumor Vessels Fuel the Fire in Glioblastoma

Glioblastoma, a subset of aggressive brain tumors, deploy several means to increase blood vessel supply dedicated to the tumor mass. This includes typical program borrowed from embryonic development, such as vasculogenesis and sprouting angiogenesis, as well as unconventional processes, including co-option, vascular mimicry, and transdifferentiation, in which tumor cells are pro-actively engaged. However, these neo-generated vascular networks are morphologically and functionally abnormal, suggesting that the vascularization processes are rather inefficient in the tumor ecosystem. In this review, we reiterate the specificities of each neovascularization modality in glioblastoma, and, how they can be hampered mechanistically in the perspective of anti-cancer therapies.

Hypoxia-dependent drivers of melanoma progression

Hypoxia, a condition of low oxygen availability, is a hallmark of tumour microenvironment and promotes cancer progression and resistance to therapy. Many studies reported the essential role of hypoxia in regulating invasiveness, angiogenesis, vasculogenic mimicry and response to therapy in melanoma. Melanoma is an aggressive cancer originating from melanocytes located in the skin (cutaneous melanoma), in the uveal tract of the eye (uveal melanoma) or in mucosal membranes (mucosal melanoma). These three subtypes of melanoma represent distinct neoplasms in terms of biology, epidemiology, aetiology, molecular profile and clinical features.In this review, the latest progress in hypoxia-regulated pathways involved in the development and progression of all melanoma subtypes were discussed. We also summarized current knowledge on preclinical studies with drugs targeting Hypoxia-Inducible Factor-1, angiogenesis or vasculogenic mimicry. Finally, we described available evidence on clinical studies investigating the use of Hypoxia-Inducible Factor-1 inhibitors or antiangiogenic drugs, alone or in combination with other strategies, in metastatic and adjuvant settings of cutaneous, uveal and mucosal melanoma.Hypoxia-Inducible Factor-independent pathways have been also reported to regulate melanoma progression, but this issue is beyond the scope of this review.As evident from the numerous studies discussed in this review, the increasing knowledge of hypoxia-regulated pathways in melanoma progression and the promising results obtained from novel antiangiogenic therapies, could offer new perspectives in clinical practice in order to improve survival outcomes of melanoma patients.

Angiomotin-p130 inhibits vasculogenic mimicry formation of small cell lung cancer independently of Smad2/3 signal pathway

Lung cancer, the most concerning malignancy worldwide and one of the leading causes of cancer-related deaths. Growing evidence indicates that Angiomotin (Amot)-p130 plays an important role in types of cancer, including breast cancer and gastric cancer. Moreover, evidence suggested that the low Amot-p130 expression correlates with the poor prognosis of lung cancer patients, however, the role and mechanism of Amot-p130 in lung cancer is still unclear. In this study, we showed that Amot-p130 expression was reduced in lung cancer tissues, compared with the adjacent para-carcinoma tissues. In addition, we observed that the reduced expression of Amot-p130 was associated with vasculogenic mimicry (VM) channels formation in lung cancer tissues. Amot-p130 expression was differently expression in lung cancer cell line H446, H1688 and H2227 compared with the normal human lung cells HFL1. To clarify the role of Amot-p130 in lung cancer, we constructed the Amot-p130 expressing H446 cells and Amot-p130 silencing H1299 cells. We confirmed that Amot-p130 overexpression inhibited the migration and invasion of lung cancer cells, whereas its silence promoted cell migration and invasion. Interestingly, we also found that Amot-p130 overexpression suppressed VM tube formation in H446 cells, while its knockdown promoted VM tube formation in H2227 cells. Further studies suggested that Amot-p130 plays roles in M tube formation of lung cancer cell V are independent on smad2/3 signaling pathway. Finally, inoculation of Amot-p130 expressing H446 cells and Amot-p130 silencing H1299 cells into nude mice suppressed tumor growth, when compared with the control group. Based on these results, Amot-p130 serves as a possible diagnostic and therapeutic target in lung cancer patients, and may be an effective mediator of VM formation in lung cancer.