Structural and functional identification of vasculogenic mimicry in vitro

The in vitro dynamics of pseudo-vascular network formation

BACKGROUND/OBJECTIVES

Pseudo-vascular network formation in vitro is considered a key characteristic of vasculogenic mimicry. While many cancer cell lines form pseudo-vascular networks, little is known about the spatiotemporal dynamics of these formations.

METHODS

Here, we present a framework for monitoring and characterising the dynamic formation and dissolution of pseudo-vascular networks in vitro. The framework combines time-resolved optical microscopy with open-source image analysis for network feature extraction and statistical modelling. The framework is demonstrated by comparing diverse cancer cell lines associated with vasculogenic mimicry, then in detecting response to drug compounds proposed to affect formation of vasculogenic mimics. Dynamic datasets collected were analysed morphometrically and a descriptive statistical analysis model was developed in order to measure stability and dissimilarity characteristics of the pseudo-vascular networks formed.

RESULTS

Melanoma cells formed the most stable pseudo-vascular networks and were selected to evaluate the response of their pseudo-vascular networks to treatment with axitinib, brucine and tivantinib. Tivantinib has been found to inhibit the formation of the pseudo-vascular networks more effectively, even in dose an order of magnitude less than the two other agents.

CONCLUSIONS

Our framework is shown to enable quantitative analysis of both the capacity for network formation, linked vasculogenic mimicry, as well as dynamic responses to treatment.

Prognostic Influence of Galectin-1 in Gastric Adenocarcinoma

Galectin-1 (Gal-1), a member of the human lectin family, has garnered attention for its association with aggressive behavior in human tumors, prompting research into the development of targeted drugs. This study aims to assess the staining pattern and prognostic significance of Gal-1 immunohistochemical expression in a homogeneous cohort of Western patients with gastric cancer (GC). A total of 149 cases were included and tissue microarrays were constructed. Stromal Gal-1 expression was observed to some extent in most tumors, displaying a cytoplasmic pattern. Cases with stromal Gal-1 overexpression showed significantly more necrosis, lymphovascular invasion, advanced pTNM stages, recurrences, and cancer-related deaths. Epithelial Gal-1 expression was present in 63.8% of the cases, primarily exhibiting a cytoplasmic pattern, and its overexpression was significantly associated with lymphovascular invasion, peritumoral lymphocytic infiltration, and tumor-related death. Kaplan/Meier curves for cancer-specific survival (CSS) revealed a significantly worse prognosis for patients with tumors exhibiting stromal or epithelial Gal-1 overexpression. Furthermore, stromal Gal-1 expression stratified stage III patients into distinct prognostic subgroups. In a multivariable analysis, increased stromal Gal-1 expression emerged as an independent prognostic factor for CSS. These findings underscore the prognostic relevance of Gal-1 and suggest its potential as a target for drug development in Western patients with GC.

Intracellular pH dynamics respond to microenvironment stiffening and mediate vasculogenic mimicry through β-catenin

Dysregulated intracellular pH (pHi) dynamics and an altered tumor microenvironment have emerged as drivers of cancer cell phenotypes. However, the molecular integration between the physical properties of the microenvironment and dynamic intracellular signaling responses remains unclear. Here, we use two metastatic cell models, one breast and one lung, to assess pHi response to varying extracellular matrix (ECM) stiffness. To experimentally model ECM stiffening, we use two tunable-stiffness hydrogel systems: Matrigel and hyaluronic acid (HA) gels, which mimic the increased protein secretion and crosslinking associated with ECM stiffening. We find that single-cell pHi decreases with increased ECM stiffness in both hydrogel systems and both metastatic cell types. We also observed that stiff ECM promotes vasculogenic mimicry (VM), a phenotype associated with metastasis and resistance. Importantly, we show that decreased pHi is both a necessary and sufficient mediator of VM, as raising pHi on stiff ECM reduces VM phenotypes and lowering pHi on soft ECM drives VM. We characterize β-catenin as a pH-dependent molecular mediator of pH-dependent VM, where stiffness-driven changes in β-catenin abundance can be overridden by increased pHi. We uncover a dynamic relationship between matrix stiffness and pHi, thus suggesting pHi dynamics can override mechanosensitive cell responses to the extracellular microenvironment.

Cyclopeptide moroidin inhibits vasculogenic mimicry formed by glioblastoma cells via regulating β-catenin activation and EMT pathways

Glioblastoma (GBM) is a highly vascularized malignant brain tumor with poor clinical outcomes. Vasculogenic mimicry (VM) formed by aggressive GBM cells is an alternative approach for tumor blood supply and contributes to the failure of anti-angiogenic therapy. To date, there is still a lack of effective drugs that target VM formation in GBM. In the present study, we evaluated the effects of the plant cyclopeptide moroidin on VM formed by GBM cells and investigated its underlying molecular mechanisms. Moroidin significantly suppressed cell migration, tube formation, and the expression levels of α-smooth muscle actin and matrix metalloproteinase-9 in human GBM cell lines at sublethal concentrations. The RNA sequencing data suggested the involvement of the epithelial-mesenchymal transition (EMT) pathway in the mechanism of moroidin. Exposure to moroidin led to a concentration-dependent decrease in the expression levels of the EMT markers N-cadherin and vimentin in GBM cells. Moreover, moroidin significantly reduced the level of phosphorylated extracellular signal-regulated protein kinase (p-ERK) and inhibited the activation of β-catenin. Finally, we demonstrated that the plant cyclopeptide moroidin inhibited VM formation by GBM cells through inhibiting the ERK/β-catenin-mediated EMT. Therefore, our study indicates a potential application of moroidin as an anti-VM agent in the treatment of GBM.

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.

Crosstalk between tumor acidosis, p53 and extracellular matrix regulates pancreatic cancer aggressiveness

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive malignancy with minimal treatment options and a global rise in prevalence. PDAC is characterized by frequent driver mutations including KRAS and TP53 (p53), and a dense, acidic tumor microenvironment (TME). The relation between genotype and TME in PDAC development is unknown. Strikingly, when wild type (WT) Panc02 PDAC cells were adapted to growth in an acidic TME and returned to normal pH to mimic invasive cells escaping acidic regions, they displayed a strong increase of aggressive traits such as increased growth in 3-dimensional (3D) culture, adhesion-independent colony formation and invasive outgrowth. This pattern of acidosis-induced aggressiveness was observed in 3D spheroid culture as well as upon organotypic growth in matrigel, collagen-I and combination thereof, mimicking early and later stages of PDAC development. Acid-adaptation-induced gain of cancerous traits was further increased by p53 knockout (KO), but only in specific extracellular matrix (ECM) compositions. Akt- and Transforming growth factor-β (TGFβ) signaling, as well as expression of the Na⁺ /H⁺ exchanger NHE1, were increased by acid adaptation. Whereas Akt inhibition decreased spheroid growth regardless of treatment and genotype, stimulation with TGFβI increased growth of WT control spheroids, and inhibition of TGFβ signaling tended to limit growth under acidic conditions only. Our results indicate that a complex crosstalk between tumor acidosis, ECM composition and genotype contributes to PDAC development. The findings may guide future strategies for acidosis-targeted therapies.

Cancer Stem Cell and Aggressiveness Traits Are Promoted by Stable Endothelin-Converting Enzyme-1c in Glioblastoma Cells

Glioblastoma (GBM) is the most common and aggressive type of brain tumor due to its elevated recurrence following treatments. This is mainly mediated by a subpopulation of cells with stemness traits termed glioblastoma stem-like cells (GSCs), which are extremely resistant to anti-neoplastic drugs. Thus, an advancement in the understanding of the molecular processes underlying GSC occurrence should contribute significantly towards progress in reducing aggressiveness. High levels of endothelin-converting enzyme-1 (ECE1), key for endothelin-1 (ET-1) peptide activation, have been linked to the malignant progression of GBM. There are four known isoforms of ECE1 that activate ET-1, which only differ in their cytoplasmic N-terminal sequences. Isoform ECE1c is phosphorylated at Ser-18 and Ser-20 by protein kinase CK2, which increases its stability and hence promotes aggressiveness traits in colon cancer cells. In order to study whether ECE1c exerts a malignant effect in GBM, we designed an ECE1c mutant by switching a putative ubiquitination lysine proximal to the phospho-serines Lys-6-to-Arg (i.e., K6R). This ECE1c^K6R mutant was stably expressed in U87MG, T98G, and U251 GBM cells, and their behavior was compared to either mock or wild-type ECE1c-expressing clone cells. ECE1c^K6R behaved as a highly stable protein in all cell lines, and its expression promoted self-renewal and the enrichment of a stem-like population characterized by enhanced neurospheroid formation, as well as increased expression of stem-like surface markers. These ECE1c^K6R-derived GSC-like cells also displayed enhanced resistance to the GBM-related chemotherapy drugs temozolomide and gemcitabine and increased expression of the ABCG2 efflux pump. In addition, ECE1c^K6R cells displayed enhanced metastasis-associated traits, such as the modulation of adhesion and the enhancement of cell migration and invasion. In conclusion, the acquisition of a GSC-like phenotype, together with heightened chemoresistance and invasiveness traits, allows us to suggest phospho-ECE1c as a novel marker for poor prognosis as well as a potential therapeutic target for GBM.

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.

FOXC2 Promotes Vasculogenic Mimicry in Ovarian Cancer

FOXC2 is a forkhead family transcription factor that plays a critical role in specifying mesenchymal cell fate during embryogenesis. FOXC2 expression is associated with increased metastasis and poor survival in various solid malignancies. Using in vitro and in vivo assays in mouse ovarian cancer cell lines, we confirmed the previously reported mechanisms by which FOXC2 could promote cancer growth, metastasis, and drug resistance, including epithelial-mesenchymal transition, stem cell-like differentiation, and resistance to anoikis. In addition, we showed that FOXC2 expression is associated with vasculogenic mimicry in mouse and human ovarian cancers. FOXC2 overexpression increased the ability of human ovarian cancer cells to form vascular-like structures in vitro, while inhibition of FOXC2 had the opposite effect. Thus, we present a novel mechanism by which FOXC2 might contribute to cancer aggressiveness and poor patient survival.

Cancer Three-Dimensional Spheroids Mimic In Vivo Tumor Features, Displaying “Inner” Extracellular Vesicles and Vasculogenic Mimicry

The role of extracellular vesicles (EVs) as mediators of cell-to-cell communication in cancer progression is widely recognized. In vitro studies are routinely performed on 2D culture models, but recent studies suggest that 3D cultures could represent a more valid model. Human ovarian cancer cells CABA I were cultured by the hanging drop method to form tumor spheroids, that were moved to low adhesion supports to observe their morphology by Scanning Electron Microscopy (SEM) and to isolate the EVs. EVs release was verified by SEM and their identity confirmed by morphology (Transmission Electron Microscopy, TEM), size distribution (Nanoparticles Tracking Analysis), and markers (CD63, CD9, TSG-101, Calnexin). CABA I form spheroids with a clinically relevant size, above 400 μm; they release EVs on their external surface and also trap “inner” EVs. They also produce vasculogenic mimicry-like tubules, that bulge from the spheroid and are composed of a hollow lumen delimited by tumor cells. CABA I can be grown as multicellular spheroids to easily isolate EVs. The presence of features typical of in vivo tumors (inner entrapped EVs and vasculogenic mimicry) suggests their use as faithful experimental models to screen therapeutic drugs targeting these pro-tumorigenic processes.

PAX2 induces vascular‑like structures in normal ovarian cells and ovarian cancer

In adult tissue, the paired box 2 (PAX2) protein is expressed in healthy oviductal, but not normal ovarian surface epithelial cells. PAX2 is expressed in a subset of cases of serous ovarian carcinoma; however, the role of PAX2 in the initiation and progression of ovarian cancer remains unknown. The aim of the present study was to determine the biological effects of PAX2 expression in normal and cancerous epithelial cells. By culturing the normal and cancerous ovarian cells that express PAX2 in 3D culture and staining the cells with vasculogenic mimicry markers such as CD31 and PAS, it was shown that PAX2 overexpression in both normal and cancerous ovarian epithelial cells induced formation of vascular-like structures both in vitro and in vivo. These results indicated a potential role of PAX2 in ovarian cancer progression by increasing the presence of vascular-like structures to promote the supply of nutrients to tumor cells and facilitate cancer cell proliferation and invasion.

Synergistic Anti-Angiogenic Effect of Combined VEGFR Kinase Inhibitors, Lenvatinib, and Regorafenib: A Therapeutic Potential for Breast Cancer

Background: Breast cancer currently affects more than two million women worldwide, and its incidence is steadily increasing. One of the most essential factors of invasion and metastasis of breast cancer cells is angiogenesis and non-angiogenic vascularization. Lenvatinib and Regorafenib share the same anti-angiogenic effect by inhibiting vascular endothelial growth factor receptors (VEGFRs subtypes 1 to 3) and have been approved for treating different types of cancer. Methods: We investigated Lenvatinib and Regorafenib effects on a well-established in-vitro model of breast cancer using MCF-7 (estrogen, progesterone receptor-positive, and HER2-negative), MDA-MB-231 (triple negative), as well as Human Umbilical Vascular Endothelial Cell line (HUVEC) cell lines. We performed the cell viability assay on four groups of cells, which included a control group, a Lenvatinib treated only group, a Regorafenib treated only group, and a group treated with a combination of both drugs at 24, 48, and 72 h. Data were analyzed as means ± standard deviation, and the drug−drug interactions with Compusyn software. Cellular migration assay, tube formation assay, and Western blots were conducted to determine the functional and the protein expression of downstream signals such as Caspase-9, anti-apoptotic Survivin, P-ERK, and total-ERK in the control and treatment groups. Results: MCF-7 cells showed a reduction in cell survival rates with higher dosing and longer incubation periods with each drug and with the combination of drugs. A synergistic interaction was identified (CI < 1) with both drugs on MCF7 at different dose combinations and at a higher dose in MDA-MB-231 cells. Furthermore, there was a marked decrease in the anti-angiogenic effect of both drugs in tube formation assay using MDA-MB-231 cells and survivin protein expression in MCF-7, and those antitumor markers showed a better outcome in drug combination than the use of each drug alone. Conclusion: Our result is the first to report the synergistic anti-angiogenic potential of combination therapy of Lenvatinib and Regorafenib. Therefore, it shows their therapeutic potential in breast cancer, including the aggressive types. Further studies are warranted to confirm and explore this therapeutic approach.

Vasculogenic Mimicry in Head and Neck Squamous Cell Carcinoma-Time to Take Notice

Head and neck squamous cell carcinoma (HNSCC) is a group of common cancers characterized by a swift growth pattern, early metastasis, and dismal 5-year survival rates. Despite the recent advances in cancer management, the multimodality approach is not effective in eradicating HNSCC. Moreover, the clinical response to the antiangiogenic therapy remains considerably limited in HNSCC patients, suggesting that tumor perfusion can take place through other non-angiogenic pathways. Tumor cell-induced angiogenesis is one of the main hallmarks of cancer. However, at the end of the previous millennium, a new paradigm of tumor cell-associated neovascularization has been reported in human melanoma cells. This new phenomenon, which was named "vasculogenic mimicry" or "vascular mimicry" (VM), describes the ability of aggressively growing tumor cells to form perfusable, matrix-rich, vessel-like networks in 3-dimensional matrices in vitro. Similar matrix-rich VM networks were also identified in tissue samples obtained from cancer patients. To date, myriad studies have reported intriguing features of VM in a wide variety of cancers including HNSCC. We aim in this mini-review to summarize the current evidence regarding the phenomenon of VM in HNSCC-from the available detection protocols and potentially involved mechanisms, to its prognostic value and the present limitations.

In Vitro Tube Formation Assays in Matrigel

Vasculature development is a combination of complex processes that require precise coordination of multiple cell types, through time and space, to generate functional blood-carrying vessels. Moreover, vasculature development can be altered when normal physiological conditions are disrupted, such as in cancer, and means to study blood vessels are of great importance. While the gold standard to explore these processes is the use of in vivo animal models, they are costly and time-consuming, and it is often difficult to dissect the molecular mechanisms involved. Thus, there are several ways to deconstruct vasculature development in vitro, in order to produce tunable systems that lead to a better understanding of cellular and molecular communication between different cell types involved, such as endothelial cells and supporting mesenchymal cells. In this method chapter, we will go into detail for one of the most popular ways of studying vasculature development in the context of cancer, which is the application of Matrigel to study tube formation of various cell types involved with vasculature development. We will provide step-by-step instructions to perform mono- and co-cultures of the major cells involved with the production of vasculature, how the results of these assays can be interpreted, and some advice to avoid common mistakes associated with Matrigel tube formation assays.

Vasculogenic Mimicry-An Overview

Vasculogenic mimicry (VM), a tumor microcirculation model found in melanoma in the last 20 years, is a vascular channel-like structure composed of tumor cells, but without endothelial cells, that stains positive for periodic acid-Schiff (PAS) and negative staining for CD31. VM provides, to the highly aggressive malignant tumor cells, adequate oxygen and nutrient supply for tumor growth and subsequent metastasis process and its presence are related to poor prognosis in patients. VM is independent of endothelial cells, which may partly explain why angiogenesis drug inhibitors have not achieved the expected success for cancer treatment.

Confocal Laser Microscopy for VM Analysis with DAPI and Phalloidin Staining

Confocal laser scanning microscopy (CLSM) is one of the most prevalent fluorescence microscopy techniques for assessing the progression of cancer cells in three-dimensional structures, such as vasculogenic mimicry (VM). We show a basic approach for using DAPI and phalloidin dyes to detect the early stages of progression and VM of melanoma tumor cells grown in a 3D environment, as well as demonstrating how to acquire images and improve them by changing the software acquisition parameters.

In Vitro Models to Study Angiogenesis and Vasculature

The development of vasculature in vivo is an extremely complex process that requires temporal and spatial coordination between multiple cell types to produce an effective vessel. The formation of vasculature from preexisting blood vessels, known as angiogenesis, plays important roles in several physiological and pathological processes, including wound healing, organ development and growth, ischemia, inflammatory disorders, fibrosis, and cancer. Means to deconstruct these complicated biological systems are necessary to gain mechanistic insight into their development, function, and modulation that can be tested in in vivo models and ultimately the clinic. In this chapter, we will first review the classical in vitro techniques to study angiogenesis. Next, we will explore the exciting recent advances that rely on 3D multicellular systems to more accurately mimic vasculature development in vitro. Finally, we will discuss the applications of in vitro angiogenic methods to study related vasculature phenomena, such as vasculogenic mimicry.

Histological Evaluation of Long-Term Collagen Type I Culture

Histological approach to long-term culture on collagen type I permits the evaluation of vasculogenic mimicry morphological features and the identification of endothelial-like cell-specific antigens. Here, we show the preparation of collagen type I solution, the embedding and the sections cutting of D17 osteosarcoma cells long-term culture, and then the hematoxylin and eosin (H&E) staining to identify endothelial-like structure. Moreover, we provide the protocols for periodic acid-Schiff (PAS) staining to evidence glycoproteins and CD31 immunohistochemistry to exclude the presence of this endothelial marker, as per definition by vasculogenic mimicry concept. This method allows to consider long-term culture as tissue, promoting the deeper study of vascular-like structures in vitro.

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.

Comparative Analysis of Vascular Mimicry in Head and Neck Squamous Cell Carcinoma: In Vitro and In Vivo Approaches

Tissue vasculature provides the main conduit for metastasis in solid tumours including head and neck squamous cell carcinoma (HNSCC). Vascular mimicry (VM) is an endothelial cell (EC)-independent neovascularization pattern, whereby tumour cells generate a perfusable vessel-like meshwork. Yet, despite its promising clinical utility, there are limited approaches to better identify VM in HNSCC and what factors may influence such a phenomenon in vitro. Therefore, we employed different staining procedures to assess their utility in identifying VM in tumour sections, wherein mosaic vessels may also be adopted to further assess the VM-competent cell phenotype. Using 13 primary and metastatic HNSCC cell lines in addition to murine- and human-derived matrices, we elucidated the impact of the extracellular matrix, tumour cell type, and density on the formation and morphology of cell-derived tubulogenesis in HNSCC. We then delineated the optimal cell numbers needed to obtain a VM meshwork in vitro, which revealed cell-specific variations and yet consistent expression of the EC marker CD31. Finally, we proposed the zebrafish larvae as a simple and cost-effective model to evaluate VM development in vivo. Taken together, our findings offer a valuable resource for designing future studies that may facilitate the therapeutic exploitation of VM in HNSCC and other tumours.

Cooperation Between Cancer and Fibroblasts in Vascular Mimicry and N2-Type Neutrophil Recruitment via Notch2-Jagged1 Interaction in Lung Cancer

Background

Angiogenesis is required for tumor development and metastasis, which is a major part in a pro-tumor microenvironment. Vascular mimicry (VM) is a process in which cancer cells, rather than endothelia, create an alternative perfusion system to support the tumor progression.

Objectives

To validate the role of VM and to develop a strategy to inhibit angiogenesis in lung cancer.

Methods

In this study, we utilized lung cancer samples to verify the existence of VM and conducted several experimental methods to elucidate the molecular pathways.

Results

H1299 and CL1-0 lung cancer cells were unable to form capillary-like structures. VM formation was induced by cancer-associated fibroblast (CAFs) in both in vitro and in vivo experiments. Notch2–Jagged1 cell–cell contact between cancer cells and CAFs contributes to the formation of VM networks, supported by Notch intracellular domain (NICD) 2 nuclear translocation and N2ICD target gene upregulated in lung cancer cells mixed with CAFs. The polarization of tumor-promoting N2-type neutrophil was increased by VM networks consisting of CAF and cancer cells. The intravasation of cancer cells and N2-type neutrophils were increased because of the loose junctions of VM. Disruption of cancer cell–CAF connections by a γ‐secretase inhibitor enforced the anticancer effect of anti‐vascular endothelial growth factor antibodies in a mouse model.

Conclusion

This study provides the first evidence that CAFs induce lung cancer to create vascular-like networks. These findings suggest a therapeutic opportunity for improving antiangiogenesis therapy in lung cancer.

Tumour cells express functional lymphatic endothelium-specific hyaluronan receptor in vitro and in vivo: Lymphatic mimicry promotes oral oncogenesis?

Lymphatic metastasis represents the main route of tumour cell dissemination in oral squamous cell carcinoma (OSCC). Yet, there are no FDA-approved therapeutics targeting cancer-related lymphangiogenesis to date. The lymphatic vessel endothelial hyaluronic acid receptor 1 (LYVE-1), a specific lymphatic marker, is associated with poor survival in OSCC patients. In this study, we present a potential novel mechanism of lymphatic metastasis in OSCC-lymphatic mimicry (LM), a process whereby tumour cells form cytokeratin⁺/LYVE-1⁺, but podoplanin-negative, mosaic endothelial-like vessels. LM was detected in one-third (20/57; 35.08%) of randomly selected OSCC patients. The LM-positive patients had shorter overall survival (OS) compared to LM-negative group albeit not statistically significant. Highly-metastatic tumour cells formed distinct LM structures in vitro and in vivo. Importantly, the siRNA-mediated knockdown of LYVE-1 not only impaired tumour cell migration but also blunted their capacity to form LM-vessels in vitro and reduced tumour metastasis in vivo. Together, our findings uncovered, to our knowledge, a previously unknown expression and function of LYVE-1 in OSCC, whereby tumour cells could induce LM formation and promote lymphatic metastasis. Finally, more detailed studies on LM are warranted to better define this phenomenon in the future. These studies could benefit the development of targeted therapeutics for blocking tumour-related lymphangiogenesis.

Canstatin represses glioma growth by inhibiting formation of VM-like structures

Vasculogenic mimicry (VM) is different from classical tumor angiogenesis and does not depend on endothelial cells. VM is closely related to the prognosis of various cancers. Canstatin was first identified as an endogenous angiogenesis inhibitor. In the present study, the inhibitory effect of canstatin on VM formation was evaluated. Human glioblastoma cell lines U87 and U251 were letivirally transduced to overexpress canstatin gene or GFP as control. In vitro assays showed that canstatin overexpression reduced the tube formation of U87 and U251 cells in Matrigel. A xenograft glioma model was created by subcutaneous injection of lentivirally modified U87 cells into nude mice. The results of in vivo experiments showed that canstatin gene introduction inhibited the growth of glioma xenografts. In tumor xenografts overexpressing canstatin, U87-mediated formation of VM-like structures and VM-related VEGF (vascular endothelial growth factor) expression were remarkably reduced. Canstatin overexpression also decreased the phosphorylation of Akt and reduced the expression of Survivin in vitro. In addition, HIF-1α production and MMP-2 secretion were decreased by canstatin overexpression. Therefore, these results suggested a protective role of canstatin during VM-like structure formation of glioma probably via inhibiting signaling pathways inducing vasculogenic mimicry.

Expression of AGGF1 and Twist1 in hepatocellular carcinoma and their correlation with vasculogenic mimicry

BACKGROUND

The most common reason for hepatocellular carcinoma (HCC) treatment failure is recurrence and metastasis. AGGF1 (a promoting gene of tumor metastasis), vasculogenic mimicry (VM, new blood supply formation in malignant tumors), and Twist1 (an evolutionarily conserved basic helix-loop-helix transcription factor) are all valuable factors for metastasis and prognosis in diverse common human cancers. However, the correlation of AGGF1, Twist1, and VM in HCC is still unclear. In this study, we analyzed the correlations among these factors as well as their correlation with clinicopathologic data and survival in HCC.

METHODS

Immunohistochemical (IHC) analysis was used to detect the expression of AGGF1 and Twist1 in 111 archival surgical specimens of human HCC. Furthermore, clinical data were collected.

RESULTS

Levels of VM, AGGF1 and Twist1 were significantly higher in HCC tissues than in normal hepatic tissues. Levels of VM, AGGF1, and Twist1 were positively associated with AFP, HBsAg, size, capsular invasion, Child-Pugh classification level, and tumor node metastasis (TNM) stage, and negatively associated with patients' overall survival (OS). In multivariate analysis, high levels of VM, AGGF1, Twist1, AFP, Child-Pugh classification level, as well as TNM stage were independently correlated with lower OS in patients with HCC.

CONCLUSION

VM and the expression of AGGF1 and Twist1 may represent promising metastatic and prognostic biomarkers, as well as therapeutic targets for HCC.

HOX Transcript Antisense RNA HOTAIR Abrogates Vasculogenic Mimicry by Targeting the AngiomiR-204/FAK Axis in Triple Negative Breast Cancer Cells

HOX transcript antisense RNA (HOTAIR) is an oncogenic long non-coding RNA frequently overexpressed in cancer. HOTAIR can enhance the malignant behavior of tumors by sponging microRNAs with tumor suppressor functions. Vasculogenic mimicry is a hypoxia-activated process in which tumor cells form three-dimensional (3D) channel-like networks, resembling endothelial blood vessels, to obtain nutrients. However, the role of HOTAIR in vasculogenic mimicry and the underlying mechanisms are unknown in human cancers. In the current study, we investigated the relevance of HOTAIR in hypoxia-induced vasculogenic mimicry in metastatic MDA-MB-231 and invasive Hs-578t triple negative breast cancer cells. Analysis of The Cancer Genome Atlas (TCGA) database using cBioPortal confirmed that HOTAIR was upregulated in clinical breast tumors relative to normal mammary tissues. Our quantitative RT-PCR assays showed a significant increase in HOTAIR levels after 48 h hypoxia relative to normoxia in breast cancer cell lines. Remarkably, knockdown of HOTAIR significantly abolished the hypoxia-induced vasculogenic mimicry which was accompanied by a reduction in the number of 3D channel-like networks and branch points. Likewise, HOTAIR silencing leads to reduced cell migration abilities of cancer cells. Bioinformatic analysis predicted that HOTAIR has a potential binding site for tumor suppressor miR-204. Luciferase reporter assays confirmed that HOTAIR is a competitive endogenous sponge of miR-204. Congruently, forced inhibition of HOTAIR in cells resulted in augmented miR-204 levels in breast cancer cells. Further bioinformatic analysis suggested that miR-204 can bind to the 3′ untranslated region of focal adhesion kinase 1 (FAK) transcript involved in cell migration. Western blot and luciferase reporter assays confirmed that FAK is a novel target of miR-204. Finally, silencing of HOTAIR resulted in low levels of cytoplasmic FAK protein and alterations in the organization of cellular cytoskeleton and focal adhesions. In summary, our results showed, for the first time, that HOTAIR mitigates cell migration and vasculogenic mimicry by targeting the miR-204/FAK axis in triple negative breast cancer cells.

Advances and Prospects of Vasculogenic Mimicry in Glioma: A Potential New Therapeutic Target?

Vasculogenic mimicry (VM) is the formation of a “vessel-like” structure without endothelial cells. VM exists in vascular-dependent solid tumors and is a special blood supply source involved in the highly invasive tumor progression. VM is observed in a variety of human malignant tumors and is closely related to tumor proliferation, invasion, and recurrence. Here, we review the mechanism, related signaling pathways, and molecular regulation of VM in glioma and discuss current research problems and the potential future applications of VM in glioma treatment. This review may provide a new viewpoint for glioma therapy.

Dynamic Culture Systems and 3D Interfaces Models for Cancer Drugs Testing

The mass use of biological agents for pharmaceutical purposes started with the development and distribution of vaccines, followed by the industrial production of antibiotics. The use of dynamic systems, such as bioreactors, had been already applied in the food industry in fermentation processes and started being used for the development of pharmaceutical agents from this point on. In the last decades, the use of bioreactors and microfluidic systems has been expanded in different fields. The emergence of the tissue engineering led to the development of in vitro models cultured in dynamic systems. This is particularly relevant considering the urgent reduction of the total dependence on animal disease models that is undermining the development of novel drugs, using alternatively human-based models to make the drug discovery process more reliable. The failure out coming from animal models has been more prevalent in certain types of cancer, such as glioblastoma multiform and in high-grade metastatic cancers like bone metastasis of breast or prostatic cancer. The difficulty in obtaining novel drugs for these purposes is mostly linked to the barriers around the tumors, which these bioactive molecules have to overcome to become effective. For that reason, the individualized study of each interface is paramount and is only realistic once applying human-based samples (e.g. cells or tissues) in three-dimensions for in vitro modeling under dynamic conditions. In this chapter, the most recent approaches to model these interfaces in 3D systems will be explored, highlighting their major contributions to the field. In this section, these systems' impact on increased knowledge in relevant aspects of cancer aggressiveness as invasive or motile cellular capacity, or even resistance to chemotherapeutic agents will have particular focus. The last section of this chapter will focus on the integration of the tumor interfaces in dynamic systems, particularly its application on high-throughput drug screening. The industrial translation of such platforms will be discussed, as well as the main upcoming challenges and future perspectives.

Roles of Remote and Contact Forces in Epithelial Cell Structure Formation

Cancer cells collectively form a large-scale structure for their growth. In this article, we report that HeLa cells, epithelial-like human cervical cancer cells, aggressively migrate on Matrigel and form a large-scale structure in a cell-density-dependent manner. To explain the experimental results, we develop a simple model in which cells interact and migrate using the two fundamentally different types of force, remote and contact forces, and show how cells form a large-scale structure. We demonstrate that the simple model reproduces experimental observations, suggesting that the remote and contact forces considered in this work play a major role in large-scale structure formation of HeLa cells. This article provides important evidence that cancer cells form a large-scale structure and develops an understanding into the poorly understood mechanisms of their structure formation.

Inhibition of Dimethylarginine Dimethylaminohydrolase (DDAH) Enzymes as an Emerging Therapeutic Strategy to Target Angiogenesis and Vasculogenic Mimicry in Cancer

The small free radical gas nitric oxide (NO) plays a key role in various physiological and pathological processes through enhancement of endothelial cell survival and proliferation. In particular, NO has emerged as a molecule of interest in carcinogenesis and tumor progression due to its crucial role in various cancer-related events including cell invasion, metastasis, and angiogenesis. The dimethylarginine dimethylaminohydrolase (DDAH) family of enzymes metabolize the endogenous nitric oxide synthase (NOS) inhibitors, asymmetric dimethylarginine (ADMA) and monomethyl arginine (L-NMMA), and are thus key for maintaining homeostatic control of NO. Dysregulation of the DDAH/ADMA/NO pathway resulting in increased local NO availability often promotes tumor growth, angiogenesis, and vasculogenic mimicry. Recent literature has demonstrated increased DDAH expression in tumors of different origins and has also suggested a potential ADMA-independent role for DDAH enzymes in addition to their well-studied ADMA-mediated influence on NO. Inhibition of DDAH expression and/or activity in cell culture models and in vivo studies has indicated the potential therapeutic benefit of this pathway through inhibition of both angiogenesis and vasculogenic mimicry, and strategies for manipulating DDAH function in cancer are currently being actively pursued by several research groups. This review will thus provide a timely discussion on the expression, regulation, and function of DDAH enzymes in regard to angiogenesis and vasculogenic mimicry, and will offer insight into the therapeutic potential of DDAH inhibition in cancer based on preclinical studies.

Galectin-1 Promotes Vasculogenic Mimicry in Gastric Cancer by Upregulating EMT Signaling

Background: Galectin-1 (Gal-1) expression was positively associated with vasculogenic mimicry (VM) in primary gastric cancer (GC) tissue, and that both Gal-1 expression and VM in GC tissue are indicators of poor prognosis. However, whether Gal-1 promotes VM, and by what mechanismsremains unknown.

Methods: To investigate the underlying mechanisms,wound healing assay, proliferation assay, invasion assay, and three-dimensional culture were used to evaluate the invasion, metastasis and promoted VM formation effects of the Gal-1. We monitored the expression level of sociated proteins in GC tissues, cell lines in vitro and nude mice tumorigenicity in vivo by immunohistochemistry and western blot.

Results: Gal-1 overexpression significantly promoted the proliferation, invasion, migration, and VM formation of MGC-803 cells. Gal-1 was associated with E-cadherin and vimentin in vitro and in clinical samples. The epithelial-to-mesenchymal transition (EMT) induced in MGC-803 cells by TGF-β1 was accompanied by Gal-1 activation and promotion of VM formation, while knockdown of Gal-1 reduced the response to TGF-β1, suggesting that Gal-1 promotes VM formation by activating EMT signaling. Overexpression of Gal-1 accelerated subcutaneous xenograft growth and facilitated pulmonary metastasis in athymic mice, enhanced the expression of EMT markers, and promoted VM formation in vivo.

Conclusion: Our results indicated that Gal-1 promotes VM in GC by upregulating EMT signaling; thus, Gal-1 and this pathway are potential novel targets to treat VM in GC.

Mechanisms of Vasculogenic Mimicry in Ovarian Cancer

Solid tumors carry out the formation of new vessels providing blood supply for growth, tumor maintenance, and metastasis. Several processes take place during tumor vascularization. In angiogenesis, new vessels are derived from endothelial cells of pre-existing vessels; while in vasculogenesis, new vessels are formed de novo from endothelial progenitor cells, creating an abnormal, immature, and disorganized vascular network. Moreover, highly aggressive tumor cells form structures similar to vessels, providing a pathway for perfusion; this process is named vasculogenic mimicry (VM), where vessel-like channels mimic the function of vessels and transport plasma and blood cells. VM is developed by numerous types of aggressive tumors, including ovarian carcinoma which is the second most common cause of death among gynecological cancers. VM has been associated with poor patient outcome and survival in ovarian cancer, although the involved mechanisms are still under investigation. Several signaling molecules have an important role in VM in ovarian cancer, by regulating the expression of genes related to vascular, embryogenic, and hypoxic signaling pathways. In this review, we provide an overview of the current knowledge of the signaling molecules involved in the promotion and regulation of VM in ovarian cancer. The clinical implications and the potential benefit of identification and targeting of VM related molecules for ovarian cancer treatment are also discussed.

Vasculogenic Mimicry: Become an Endothelial Cell "But Not So Much"

Blood vessels supply all body tissues with nutrients and oxygen, take away waste products and allow the arrival of immune cells and other cells (pericytes, smooth muscle cells) that form part of these vessels around the principal endothelial cells. Vasculogenic mimicry (VM) is a tumor blood supply system that takes place independently of angiogenesis or endothelial cells, and is associated with poor survival in cancer patients. Aberrant expression of VE-cadherin has been strongly associated with VM. Even more, VE-cadherin has constitutively high phosphorylation levels on the residue of Y658 in human malignant melanoma cells. In this review we focus on non-endothelial VE-cadherin and its post-translational modifications as a crucial component in the development of tumor VM, highlighting the signaling pathways that lead to their pseudo-endothelial and stem-like phenotype and the role of tumor microenvironment. We discuss the importance of the tumor microenvironment in VM acquisition, and describe the most recent therapeutic targets that have been proposed for the repression of VM.

Fact or Fiction, It Is Time for a Verdict on Vasculogenic Mimicry?

The term vasculogenic mimicry (VM) refers to the capacity of certain cancer cells to form fluid-conducting structures within a tumor in an endothelial cell (EC)-free manner. Ever since its first report by Maniotis in 1999, the existence of VM has been an extremely contentious issue. The overwhelming consensus of the literature suggests that VM is frequently observed in highly aggressive tumors and correlates to lower patient survival. While the presence of VM in vivo in animal and patient tumors are claimed upon the strong positive staining for glycoproteins (Periodic Acid Schiff, PAS), it is by no means universally accepted. More controversial still is the existence of an in vitro model of VM that principally divides the scientific community. Original reports demonstrated that channels or tubes occur in cancer cell monolayers in vitro when cultured in matrigel and that these structures may support fluid movement. However, several years later many papers emerged stating that connections formed between cancer cells grown on matrigel represented VM. We speculate that this became accepted by the cancer research community and now the vast majority of the scientific literature reports both presence and mechanisms of VM based on intercellular connections, not the presence of fluid conducting tubes. In this opinion paper, we call upon evidence from an exhaustive review of the literature and original data to argue that the majority of in vitro studies presented as VM do not correspond to this phenomenon. Furthermore, we raise doubts on the validity of concluding the presence of VM in patient samples and animal models based solely on the presence of PAS+ staining. We outline the requirement for new biomarkers of VM and present criteria by which VM should be defined in vitro and in vivo.

cRGD-functionalized nanoparticles for combination therapy of anti-endothelium dependent vessels and anti-vasculogenic mimicry to inhibit the proliferation of ovarian cancer

Accumulating evidence has disclosed effective anti-angiogenic strategies should simultaneously inhibit endothelium-dependent vessels (EDV) and tumor cell-mediated vasculogenic mimicry (VM). The α_vβ₃ integrin-targeting peptide cRGD has the ability to inhibit EDV and we have found cRGD can also suppress the formation of VM in ovarian cancer cells. Herein, a cRGD-based combination strategy was developed to suppress the proliferation of tumor cells by anti-EDV and anti-VM. We firstly engineered two cRGD functionalized nanoparticles (cRGD-NPs1 and cRGD-NPs2) by self-assembly using heparin conjugated with cRGD and folate. In vitro experiments demonstrated cRGD-NPs2 exhibited more significant cytotoxicity and higher intracellular uptake ability than cRGD-NPs1. Also, cRGD-NPs2 could efficiently discourage EDV, VM and proliferation in HUVECs and SKOV3 (VM+) cells. In vivo studies showed cRGD-NPs2 could specifically accumulate in ovarian cancer tissues and exerted a superior anti-tumor effect in SKOV3 xenografts. The mechanisms responsible for creating anti-EDV and anti-VM action of cRGD-NPs2 related to combined effects of cRGD, heparin and folate. The results demonstrated cRGD-NPs2 represented a versatile anti-angiogenic medicine via their combined inhibitory effect. STATEMENT OF SIGNIFICANCE: Accumulating documents indicate tumor cell-mediated vasculogenic mimicry (VM) is positively correlated with poor prognosis, occurrence of distant metastasis and low survival rate in cancer patients, suggesting VM is a potential therapeutic target for cancer treatment. Thus, effective anti-angiogenic strategies should simultaneously inhibit VM as well as endothelium-dependent vessels (EDV). Integrin α_vβ₃ is a crucial inducer involved in the formation of both EDV and VM. In this study, we engineered α_vβ₃ integrin-targeting peptide cRGD functionalized nanoparticles (cRGD-NPs) by self-assembly using heparin conjugated with cRGD and folate. The prepared cRGD-NPs represent a promising anti-angiogenic medicine in that they are able to inhibit endothelial sprouting angiogenesis and tumor cell-mediated VM. This work may provide useful information with which to construct effective anti-angiogenic nanomedicines.

HypoxamiRs Profiling Identify miR-765 as a Regulator of the Early Stages of Vasculogenic Mimicry in SKOV3 Ovarian Cancer Cells

Vasculogenic mimicry (VM) is a novel cancer hallmark in which malignant cells develop matrix-associated 3D tubular networks with a lumen under hypoxia to supply nutrients needed for tumor growth. Recent studies showed that microRNAs (miRNAs) may have a role in VM regulation. In this study, we examined the relevance of hypoxia-regulated miRNAs (hypoxamiRs) in the early stages of VM formation. Data showed that after 48 h hypoxia and 12 h incubation on matrigel SKOV3 ovarian cancer cells undergo the formation of matrix-associated intercellular connections referred hereafter as 3D channels-like structures, which arose previous to the apparition of canonical tubular structures representative of VM. Comprehensive profiling of 754 mature miRNAs at the onset of hypoxia-induced 3D channels-like structures showed that 11 hypoxamiRs were modulated (FC>1.5; p < 0.05) in SKOV3 cells (9 downregulated and 2 upregulated). Bioinformatic analysis of the set of regulated miRNAs showed that they might impact cellular pathways related with tumorigenesis. Moreover, overall survival analysis in a cohort of ovarian cancer patients (n = 485) indicated that low miR-765, miR-193b, miR-148a and high miR-138 levels were associated with worst patients outcome. In particular, miR-765 was severely downregulated after hypoxia (FC < 32.02; p < 0.05), and predicted to target a number of protein-encoding genes involved in angiogenesis and VM. Functional assays showed that ectopic restoration of miR-765 in SKOV3 cells resulted in a significant inhibition of hypoxia-induced 3D channels-like formation that was associated with a reduced number of branch points and patterned tubular-like structures. Mechanistic studies confirmed that miR-765 decreased the levels of VEGFA, AKT1 and SRC-α transducers and exerted a negative regulation of VEGFA by specific binding to its 3'UTR. Finally, overall survival analysis of a cohort of ovarian cancer patients (n = 1435) indicates that high levels of VEGFA, AKT1 and SRC-α and low miR-765 expression were associated with worst patients outcome. In conclusion, here we reported a novel hypoxamiRs signature which constitutes a molecular guide for further clinical and functional studies on the early stages of VM. Our data also suggested that miR-765 coordinates the formation of 3D channels-like structures through modulation of VEGFA/AKT1/SRC-α axis in SKOV3 ovarian cancer cells.

Serum promotes vasculogenic mimicry through the EphA2/VE-cadherin/AKT pathway in PC-3 human prostate cancer cells

AIMS

Serum is widely used for in vitro cell culture of eukaryotic cells. Although serum is well known to affect various biological activities in cancer cells, its effect in vasculogenic mimicry (VM) is not yet fully defined. Thus, this study investigated the role of serum in VM in human prostate cancer (PCa) PC-3 cells.

MAIN METHODS

Invasion assay and 3D culture VM tube formation assay are performed. VM-related molecules are checked by western blot and reverse transcriptase-polymerase chain reaction. Nuclear twist is detected by confocal after twist-FITC/DAPI double staining.

KEY FINDINGS

Serum dramatically induced not only invasion but also VM. Serum increased the phosphorylation of erythropoietin-producing hepatocellular A2 (EphA2) without affecting EphA2 expression. Both the protein and mRNA expression levels of vascular endothelial cadherin (VE-cadherin) are up-regulated by serum. Twist expression was increased in the nucleus by serum. Serum activated AKT through phosphorylation, despite the unchanged AKT expression. Serum caused an increase in matrix metalloproteinase-2 (MMP-2) and laminin subunit 5 gamma-2 (LAMC2) protein expressions. Wortmannin, a phosphoinositide-3-kinase inhibitor, significantly decreased serum-induced invasion and VM.

SIGNIFICANCE

These results demonstrated that serum activates EphA2 and up-regulates twist/VE-cadherin, which in turn activate AKT that up-regulates MMP-2 and LAMC2, thereby inducing the invasion and VM of human PCa PC-3 cells.

Dendrimer Heparan Sulfate Glycomimetics: Potent Heparanase Inhibitors for Anticancer Therapy

Heparanase is a mammalian endoglycosidase that cleaves heparan sulfate (HS) polysaccharides and contributes to remodelling of the extracellular matrix and regulation of HS-binding protein bioavailabilities. Heparanase is upregulated in malignant cancers and inflammation, aiding cell migration and the release of signaling molecules. It is established as a highly druggable extracellular target for anticancer therapy, but current compounds have limitations, because of cost, production complexity, or off-target effects. Here, we report the synthesis of a novel, targeted library of single-entity glycomimetic clusters capped with simple sulfated saccharides. Several dendrimer HS glycomimetics display low nM IC₅₀ potency for heparanase inhibition equivalent to comparator compounds in clinical development, and potently inhibit metastasis and growth of human myeloma tumor cells in a mouse xenograft model. Importantly, they lack anticoagulant activity and cytotoxicity, and also inhibit angiogenesis. They provide a new candidate class for anticancer and wider therapeutic applications, which could benefit from targeted heparanase inhibition.

Prognostic significance of galectin-1 and vasculogenic mimicry in patients with gastric cancer

INTRODUCTION

We evaluated the expression of galectin-1 (Gal-1) and vasculogenic mimicry (VM) in gastric cancer (GC) and investigated their relationships with the clinicopathological factors and prognostic significance in GC.

MATERIALS AND METHODS

Immunohistochemical (IHC) staining and CD34-periodic acid-Schiff double stain were used to investigate Gal-1 expression and VM in paraffin-embedded sections from 127 patients with GC of all tumor stages. The relationships between Gal-1 expression and VM, clinicopathological variables, and survival were analyzed. P < 0.05 was considered statistically significant.

RESULTS

Among the 127 cases, 86 (67.7%) were positive for Gal-1; VM was detected in 29 cases (22.8%). There was a significant association between VM and the Gal-1 IHC staining; all cases with VM were positive for Gal-1 staining. Gal-1 expression and VM in primary GC tissue were associated with tumor size, differentiation, depth of tumor invasion, stage, lymph node metastases, and tumor emboli in microvessels (all, P < 0.05). Kaplan-Meier analysis revealed that the overall survival time was 52.56 ± 2.44 months (95% confidence interval [CI]: 47.77-57.35) for patients with Gal-1-negative and VM-negative primary GC tissue, 43.83 ± 2.17 months (95% CI: 39.58-48.08) for patients with Gal-1-positive but VM-negative primary GC tissue, and 23.97 ± 2.44 months (95% CI: 19.18-28.76) for patients with Gal-1-positive and VM-positive primary GC tissue (χ² = 60.21, P < 0.01). Gal-1 expression was positively associated with VM in primary GC tissue.

CONCLUSION

Both Gal-1 expression and VM in primary GC tissue are indicators of poor prognosis for GC after gastrectomy, and Gal-1 may be a novel target for treating VM in GC.

Collateral Damage Intended-Cancer-Associated Fibroblasts and Vasculature Are Potential Targets in Cancer Therapy

After oncogenic transformation, tumor cells rewire their metabolism to obtain sufficient energy and biochemical building blocks for cell proliferation, even under hypoxic conditions. Glucose and glutamine become their major limiting nutritional demands. Instead of being autonomous, tumor cells change their immediate environment not only by their metabolites but also by mediators, such as juxtacrine cell contacts, chemokines and other cytokines. Thus, the tumor cells shape their microenvironment as well as induce resident cells, such as fibroblasts and endothelial cells (ECs), to support them. Fibroblasts differentiate into cancer-associated fibroblasts (CAFs), which produce a qualitatively and quantitatively different extracellular matrix (ECM). By their contractile power, they exert tensile forces onto this ECM, leading to increased intratumoral pressure. Moreover, along with enhanced cross-linkage of the ECM components, CAFs thus stiffen the ECM. Attracted by tumor cell- and CAF-secreted vascular endothelial growth factor (VEGF), ECs sprout from pre-existing blood vessels during tumor-induced angiogenesis. Tumor vessels are distinct from EC-lined vessels, because tumor cells integrate into the endothelium or even mimic and replace it in vasculogenic mimicry (VM) vessels. Not only the VM vessels but also the characteristically malformed EC-lined tumor vessels are typical for tumor tissue and may represent promising targets in cancer therapy.