Tumor Vasculogenic Mimicry Research Articles

Wnt5a promotes VM formation by modulating the stemness and EMT progression of prostate cancer cell.

The incidence of prostate cancer (PCa) is increasing annually, making it the leading cause of tumor-related mortality in males. The available treatment options for metastatic PCa are limited. Vasculogenic mimicry (VM), an emerging phenomenon involving aggressive tumor cells, has a significant impact on patient survival. Misregulation of Wnt5a expression is commonly observed during cancer progression. However, there is a lack of comprehensive studies investigating the effects of Wnt5a on tumor VM formation. In this study, we demonstrate that alterations in wnt5a expression, either through gain or loss, have a significant influence on the formation of VM in tumor cells mediated by cell stemness and EMT progression. Further research has demonstrated that Wnt5a regulates the formation of VM through the PI3K/JNK signaling pathway. These experimental findings offer a novel avenue for the clinical management of prostate cancer.

Pseudogene MAPK6P4-encoded functional peptide promotes glioblastoma vasculogenic mimicry development

Glioma is the most common primary malignancy of the central nervous system. Glioblastoma (GBM) has the highest degree of malignancy among the gliomas and the strongest resistance to chemotherapy and radiotherapy. Vasculogenic mimicry (VM) provides tumor cells with a blood supply independent of endothelial cells and greatly restricts the therapeutic effect of anti-angiogenic tumor therapy for glioma patients. Vascular endothelial growth factor receptor 2 (VEGFR2) and vascular endothelial cadherin (VE-cadherin) are currently recognized molecular markers of VM in tumors. In the present study, we show that pseudogene MAPK6P4 deficiency represses VEGFR2 and VE-cadherin protein expression levels, as well as inhibits the proliferation, migration, invasion, and VM development of GBM cells. The MAPK6P4-encoded functional peptide P4-135aa phosphorylates KLF15 at the S238 site, promoting KLF15 protein stability and nuclear entry to promote GBM VM formation. KLF15 was further confirmed as a transcriptional activator of LDHA, where LDHA binds and promotes VEGFR2 and VE-cadherin lactylation, thereby increasing their protein expression. Finally, we used orthotopic and subcutaneous xenografted nude mouse models of GBM to verify the inhibitory effect of the above factors on GBM VM development. In summary, this study may represent new targets for the comprehensive treatment of glioma.

Vasculogenic mimicry in tumors – current state of the issue

Введение. В ходе эволюции злокачественные новообразования приобретали различные механизмы, направленные на ускорение роста и повышение вероятности метастазирования. Одним из таких механизмов является васкулогенная мимикрия, способствующая транспортировке плазмы и форменных элементов крови, минуя классические пути опухолевого ангиогенеза. Цель исследования – изучить молекулярные механизмы, особенности микроскопической картины васкулогенной мимикрии, обозначить ее роль в опухолевом процессе. Материал и методы. Осуществлен ретроспективный анализ более 70 отечественных и зарубежных научных и клинических исследований, а также обзорных статей, посвященных васкулогенной мимикрии. Заключение. Определение роли и точных механизмов васкулогенной мимикрии в канцерогенезе, позволит разработать комплекс профилактических и лечебных мероприятий, направленных на регресс опухолевого роста и предотвращение раннего метастазирования.

Effect of LHS-1269 on morphology and angiogenesis of Lewis lung carcinoma

Background. The new anticancer chemical compound LHS-1269 from the class of indolocarbazoles is undergoing preclinical studies at the N.N. Blokhin National Medical Research Center of Oncology, Ministry of Health of Russia. LHS-1269 has a high antitumor activity on transplanted tumors of mice, showed high cytotoxic activity on many tumor cells lines in vitro, and has shown an inhibitory effect on vasculogenic mimicry in tumors in vitro. LHS-1269 does not affect the catalytic activity of human topoisomerases I and IIα. An antiangiogenic mechanism of the drug’s antitumor action is suggested.Aim. To evaluate the effect of LHS-1269 on the morphological features and angiogenesis of transplanted Lewis lung carcinoma (LLC) in BDF1 mice.Materials and methods. In BDF1 mice (n = 20) with transplanted LLC tumor on days 1 and 3 after 5-fold intraperitoneal administration of LHS-1269 in a single dose of 60 mg (total dose – 300 mg/kg), mice (n = 20) on days 5 and 8 after a single intravenous injection of LHS-1269 at a dose of 100 mg/kg, mice (n = 20) with transplanted LLC tumor without administration of LHS-1269 (control). The assessment of the antitumor effect was carried out according to the criterion of inhibition of tumor growth (%) and the study of the morphological features of the tumors. To assess the effect of LHS-1269 on tumor angiogenesis in LLC tumor sections, a visual calculation of the average number (density) of blood vessels and immunohistochemical detection of expression of the CD31+ endothelial marker were performed.Results. The LHS-1269 compound in animal groups with 5-fold and 1-fold use caused tumor growth inhibition – 59–70 and 67–79 %, with pronounced morphological changes and tumor cell death. There is an uneven distribution of blood vessels in tumors and surrounding tissues in all groups. LHS-1269 caused a statistically significant decrease in the average number of blood vessels in the tumor both after 5-fold and after 1-fold administration. The statistically significant decrease in the average number of blood vessels in the surrounding connective tissue tumor was observed only after 5-fold administration of the drug. The decrease in the average number of CD31+ endothelial cells after five times intraperitoneal administration was statistically insignificant compared to control (83.1 ± 8.7 and 59.6 ± 18.9, respectively). The increase in this indicator after a single intravenous injection of LHS-1269 was statistically significant.Conclusion. LHS-1269, when administered five times and once in mice, caused pronounced morphological changes in the form of damage and death of LLC tumor cells. The results of a study of angiogenesis in a tumor do not allow an unambiguous conclusion about the inhibitory effect of LHS-1269 on angiogenesis in LLC tumors in mice.

LncRNA n339260 functions in hepatocellular carcinoma progression via regulation of miRNA30e-5p/TP53INP1 expression.

Currently, the molecular mechanism of the interaction between lncRNAs and microRNAs (miRNAs) and the target of miRNAs in tumor vasculogenic mimicry (VM) formation have not been clarified. Our aim is to study the interaction between lncRNA n339260 and miRNA30e-5p in the formation of VM. Animal xenografts were established, 104 hepatocellular carcinoma (HCC) patients' frozen tissues were obtained and HCC cells in vitro were used to observe the role of n339260 in HCC progression. In vivo experiment showed lncRNA n339260 promoted tumor growth and VM formation. LncRNA n339260 and miRNA30e-5p were found to be associated with VM formation, metastasis and survival time in HCC patients. In vitro experiment showed that LncRNA n339260 could inhibit miRNA30e-5p expression and TP53INP1 was found to be the downstream targets of miRNA30e-5p. Snail, MMP2, MMP9, VE-cadherin, vimentin and N-cadherin overexpression and the downregulation of TP53INP1 and E-cadherin were observed in HCCLM3 and HepG2 cells overexpressing lncRNA n339260 or in cells with decreased expression of miRNA30e-5p. LncRNA n339260 promotes the development of VM, and lncRNA n339260 may enhance Snail expression by decreasing the expression of miRNA30e-5p, thereby reducing TP53INP1 expression. Therefore, a potential lncRNA n339260- miRNA30e-5p- TP53INP1 regulatory axis was associated with HCC progression.

Coupled fibromodulin and SOX2 signaling as a critical regulator of metastatic outgrowth in melanoma

We aimed to study mechanisms controlling metastatic outgrowth of melanoma into clinically relevant lesions, a critical process responsible for the majority of melanoma deaths. To this end, we developed novel in vivo models and identified molecular events that can be ascribed to their distinct phenotypes, indolent or highly metastatic. Induction of a proliferative state at distant sites was associated with high levels of the stem-like/progenitor marker, SOX2, and required the upregulation of FMOD, an extracellular matrix component, which modulates tumor–stroma interactions. Functional studies revealed a possible link between FMOD and SOX2; dual FMOD and SOX2 silencing nearly abolished brain metastasis and had a similar effect on distant metastasis to other sites. Our in vitro data suggests that FMOD and SOX2 cooperation plays an important role in tumor vasculogenic mimicry. Furthermore, we found that FMOD and SOX2 functional roles might converge at the activation of transcriptional co-factors YAP and TAZ, possibly via crosstalk with the tumor suppressor Hippo pathway. Finally, high expression of both genes in patient specimens predicted early development of brain metastasis. Thus, our study identifies FMOD and SOX2 cooperation as a novel regulatory mechanism that might be linked functionally to melanoma metastatic competence.

Vitamin D Exerts Significant Antitumor Effects by Suppressing Vasculogenic Mimicry in Breast Cancer Cells.

BackgroundNumerous clinical and experimental observations have alluded to the substantial anti-neoplastic role of vitamin D in breast cancer (BC), primarily by inducing apoptosis and affecting metastasis. Tumor progression and resistance to chemotherapy have been linked to vasculogenic mimicry (VM), which represents the endothelial-independent formation of microvascular channels by cancer cells. However, the effect of vitamin D on VM formation in BC has not been thoroughly investigated. This study examined the impact of 1α,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, on the expression of major factors involved in BC migration, invasion, and VM formation.Experimental MethodsPublicly available transcriptomic datasets were used to profile the expression status of the key VM markers in vitamin D-treated BC cells. The in silico data were validated by examining the expression and activity of the key factors that are involved in tumor progression and MV formation in hormone-positive MCF-7 and aggressive triple‐negative MDA-MB-231 BC cells after treatment with calcitriol.Results and DiscussionsThe bioinformatics analysis showed that tumor VM formation-enriched pathways were differentially downregulated in vitamin D-treated cells when compared with control counterparts. Treatment of BC cells with calcitriol resulted in increased expression of tissue inhibitors of metalloproteinases (TIMPs 1 and 2) and decreased content and gelatinolytic activity of matrix metalloproteinases (MMPs 2 and 9). Furthermore, calcitriol treatment reduced the expression of several pro-MV formation regulators including vascular endothelial growth factor (VEGF), tumor growth factor (TGF-β1), and amphiregulin. Eventually, this process resulted in a profound reduction in cell migration and invasion following the treatment of BC cells with calcitriol when compared to the controls. Finally, the formation of VM was diminished in the aggressive triple‐negative MDA-MB-231 cancer cell line after calcitriol treatment.ConclusionOur findings demonstrate that vitamin D mediates its antitumor effects in BC cells by inhibiting and curtailing their potential for VM formation.

Application of IVIM-DWI in Detecting the Tumor Vasculogenic Mimicry Under Antiangiogenesis Combined With Oxaliplatin Treatment.

Objectives: This study aimed to detect the time window of vascular normalization during anti-vascular treatment using intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI). Simultaneously, we evaluated the tumor invasiveness and vasculogenic mimicry and performed synthetic assessment of treatment efficacy of angiogenesis inhibitor combined with conventional chemotherapy using IVIM-DWI.Materials and Methods: HCT116 cells were subcutaneously administered into the right flank of BALB/C nude mice to build a colon cancer xenograft model. Thirty-two tumor-bearing mice were randomly divided into four groups and intraperitoneally administered with normal saline (Group A or control group), bevacizumab (Group B), oxaliplatin monotherapy (Group C), and oxaliplatin combined with bevacizumab (Group D). The IVIM-DWI was performed on days 0, 3, 6, 9, 12, and 15 after the treatments. Another 51 tumor-bearing mice were included in the pathological examinations. α-Smooth muscle actin (SMA) and CD31 double-staining, periodic acid-Schiff (PAS) and CD31 double-staining, hematoxylin and eosin (HE), Ki-67, and E-cadherin staining were performed. The tumor growth and dynamic change of each parameter were noted.Results: The mice in Group D manifested the smallest tumor volume and highest tumor inhibition rate. Microvessel density was significantly decreased but accompanied by increased vasculogenic mimicry after antiangiogenic treatment. The trend was reversed by oxaliplatin treatment. Treated with bevacizumab, the vessel maturity index shared a similar trend with D* and f-values during days 3–12, which slowly increased from days 0 to 9 and then decreased briefly. D-value significantly correlated with vasculogenic mimicry and Ki-67, while D* and f-values showed positive correlations with microvessel density and E-cadherin, an indicator of epithelial–mesenchymal transition.Conclusion: Oxaliplatin performed an inhibited effect on vasculogenic mimicry. Bevacizumab can enhance the tumor chemotherapy through vascular normalization within a transient time period, which can be detected by IVIM-DWI. D* and f-values are able to predict the tumor invasiveness while D is superior in reflecting vasculogenic mimicry and Ki-67 expression during antitumor treatment.

Study on the expression of non-coding microRNA-376b-3p in serum exosomes of patients with malignant glioma and the mechanism of anti-angiogenesis

Objective: To screen the different microRNAs in the serum exosomes of patients with malignant glioma, to explore the effect of non-coding microRNA-376b-3p (miR-376b-3p) on the proliferation, invasion and tumor vasculogenic mimicry of glioma cells, and to verify its targeting effect on HOXD10. Methods: HiSeq/MiSeq high-throughput sequencing was used to screen the different microRNA expression profiles, target genes and action pathways in the serum exosomes of patients with malignant glioma. Samples were used to evaluate the expression of candidate microRNAs in serum exosomes of high-grade gliomas. The effects of miR-376b-3p on the proliferation, invasion and angiogenesis of glioma cells were detected by MTT assay, Transwell migration assay and Matrigel vasculogenic mimicry assay. The mRNA and protein expression of HOXD10 were detected to evaluate the regulatory effect of miR-376b-3p on it. Results: There were 144 different expression microRNAs in the serum exosomes between malignant glioma and the normal control. Focal adhesion and tumor protein polysaccharides were involved in the regulation of glioma enriched by KEGG(Kyoto Encyclopedia of Genes and Genomes). MiR-376b-3p was down regulated in malignant glioma, and AUC of malignant glioma was 0.85 (P<0.01). MTT test showed that the proliferation ability of miR-376b-3p inhibitor group was higher than that of the control group, and that of miR-376b-3p mimic group was lower than that of the control group. Transwell migration test showed that the number of transmembrane cells in miR-376b-3p inhibitor group was higher than that in NC inhibitor group, and the number of transmembrane cells in miR-376b-3p mimic group was lower than that in NC mimic group. The number of tubes of vasculogenic mimicry in miR-376b-3p mimic group was lower than that in NC mimic group. MiR-376b-3p inhibitor decreased the expression level of HOXD10 mRNA and protein, and miR-376b-3p mimic increased the expression level of HOXD10 mRNA and protein. Conclusions: MiR-376b-3p is down-regulated in the serum exosomes of malignant glioma patients. The up-regulated miR-376b-3p can reduce the proliferation and invasion of glioma cells, inhibit the formation of vasculogenic mimicry, and increase the expression of HOXD10, which is expected to inhibit the formation of two forms of angiogenesis at the same time. MiR-376b-3p may be a new therapeutic target of anti-angiogenesis for malignant glioma.

Effect of Derivatives of Hydroxamic Acids on Vasculogenic Mimicry

Vasculogenic mimicry, the formation of vascular channels lined with tumor cells of a highly malignant phenotype, is currently considered as an additional system of blood supply of the tumor. Experimental studies in vivo have repeatedly demonstrated that vascular channels form in the areas of a tumor with a low density of blood vessels. It is supposed that the formation of a network of these channels inside the tumor maintains homeostasis and prevents early necrosis within it. In this work, bifunctional compounds based on a combination of quinazoline and hydroxamic acid in one molecule were examined for the ability to inhibit the migration of tumor cells and vasculogenic mimicry.

Regulation Networks Driving Vasculogenic Mimicry in Solid Tumors.

Vasculogenic mimicry (VM) is a mechanism whereby cancer cells form microvascular structures similar to three-dimensional channels to provide nutrients and oxygen to tumors. Unlike angiogenesis, VM is characterized by the development of new patterned three-dimensional vascular-like structures independent of endothelial cells. This phenomenon has been observed in many types of highly aggressive solid tumors. The presence of VM has also been associated with increased resistance to chemotherapy, low survival, and poor prognosis. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are non-coding RNAs that regulate gene expression at the post-transcriptional level through different pathways. In recent years, these tiny RNAs have been shown to be expressed aberrantly in different human malignancies, thus contributing to the hallmarks of cancer. In this context, miRNAs and lncRNAs can be excellent biomarkers for diagnosis, prognosis, and the prediction of response to therapy. In this review, we discuss the role that the tumor microenvironment and the epithelial-mesenchymal transition have in VM. We include an overview of the mechanisms of VM with examples of diverse types of tumors. Finally, we describe the regulation networks of lncRNAs-miRNAs and their clinical impact with the VM. Knowing the key genes that regulate and promote the development of VM in tumors with invasive, aggressive, and therapy-resistant phenotypes will facilitate the discovery of novel biomarker therapeutics against cancer as well as tools in the diagnosis and prognosis of patients.

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.

Vasculogenic mimicry in melanoma: molecular mechanisms and clinical significance

The concept of vasculogenic mimicry (VM) was introduced to describe the unique ability of highly aggressive tumor cells to form capillary-like structures and matrix-rich patterned network in three-dimensional culture that mimic embryonic vasculogenic network. VM has been reported in several aggressive tumors including ovaries, breast, liver, lung cancer, sarcoma, glioblastoma. It is worth to note, that VM in melanocyte-originated tumors is the most studied. Although much attention has been focused on factors that stimulate or suppress vascular channel formation by tumor cells, the molecular mechanisms underlying this phenomenon remain enigmatic. This review will focus on molecular determinants and key signaling pathways involved in tumor VM. The exploration of drugs targeted at molecular signaling pathways in VM is a field of challenges and hopes. The research on VM will increase our knowledge of the molecular events causing aggressive tumor cells to gain plasticity resulting in their ability to mimic vasculature. To date, little functional data exist that show how tumor cell-lined channels contribute to the overall survival of the tumor. However, even among researches who have questioned the concept of VM as a crucial circulatory system, there is generally a consensus that the prognostic significance of PAS-positive patterns is valid.

Correlation Between Tumor Vasculogenic Mimicry and Poor Prognosis of Human Digestive Cancer Patients: A Systematic Review and Meta-Analysis.

Vasculogenic mimicry (VM) is a new pattern of blood supplement independent of endothelial vessels, which is related with tumor invasion, metastasis and prognosis. However, the role of VM in the prognosis of cancer patients is controversial. This study aimed to perform a meta-analysis of the published data to attempt to clarify the prognostic value of VM in the digestive cancer. Relevant studies were retrieved from the PubMed, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure and VIP databases published before March 29, 2018. Studies were included if they detected VM in the digestive cancer and analyzed the overall survival (OS) or disease-free survival (DFS) according to VM status. Two independent reviewers screened the studies, extracted data, and evaluated the quality of included studies with the Newcastle-Ottawa scale. Meta-analysis was performed using STATA 12.0 software. A total of 22 studies with 2411 patients were included in this meta-analysis. Meta-analysis showed that VM was related with the poor OS (HR = 2.30, 95% CI: 2.06-2.56, P < 0.001) and DFS (HR = 2.60, 95% CI: 2.07-3.27, P < 0.001) of patients with digestive cancer. Subgroup analysis showed VM was related with tumor differentiation, lymph node metastasis and TNM stage. Moreover, the present meta-analysis was reliable, and there was no obvious publication bias. This meta-analysis suggested that VM was a poor prognosis of digestive cancer patients. Further large and well-designed studies are required.

Hsp90β promotes aggressive vasculogenic mimicry via epithelial-mesenchymal transition in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a typical hypervascular solid tumor. Vasculogenic mimicry (VM) formed by aggressive tumor cells to mimic vasculogenic networks plays an important role in the tumor malignancy of HCC. Hsp90β promotes endothelial cell-dependent angiogenesis in HCC. However, the relationship between Hsp90β and VM formation is unclear. In this study, we found that Hsp90β is positively correlated with VM and EMT marker proteins in HCC tissues and promotes tube formation, cell migration, and invasion in vitro. Hsp90β interacts with Twist1 and promotes its deubiquitination and stabilization to nuclear translocation and enhances the VE-cadherin promoter activity. Results of in vitro analysis indicate that Hsp90β enhances the tumor VM in tumor-burdened mice, and the Hsp90 inhibitor NVP-BEP800 suppresses VM formation by releasing Hsp90β and Twist1 interaction. This study provides a potential antitumor therapy for inhibiting VM by targeting Hsp90β in HCC.

A LATS biosensor screen identifies VEGFR as a regulator of the Hippo pathway in angiogenesis

The Hippo pathway is a central regulator of tissue development and homeostasis, and has been reported to have a role during vascular development. Here we develop a bioluminescence-based biosensor that monitors the activity of the Hippo core component LATS kinase. Using this biosensor and a library of small molecule kinase inhibitors, we perform a screen for kinases modulating LATS activity and identify VEGFR as an upstream regulator of the Hippo pathway. We find that VEGFR activation by VEGF triggers PI3K/MAPK signaling, which subsequently inhibits LATS and activates the Hippo effectors YAP and TAZ. We further show that the Hippo pathway is a critical mediator of VEGF-induced angiogenesis and tumor vasculogenic mimicry. Thus, our work offers a biosensor tool for the study of the Hippo pathway and suggests a role for Hippo signaling in regulating blood vessel formation in physiological and pathological settings.

Cancer/testis Antigen MAGEA3 Interacts with STAT1 and Remodels the Tumor Microenvironment.

Cancer-testis antigen MAGEA3, being restrictedly expressed in testis and various kinds of tumors, has long been considered as an ideal target for immunotherapy. In this study, we report that MAGEA3 interacts with STAT1 and regulates the expression of tyrosine phosphorylated STAT1 (pY-STAT1) in tumor cells. We show that pY-STAT1 is significantly up-regulated when MAGEA3 is silenced by MAGEA3-specific siRNA. RNA sequencing analysis identified 274 STAT1-related genes to be significantly altered in expression level in MAGEA3 knockdown cells. Further analysis of these differentially expressed genes with GO enrichment and KEGG pathway revealed that they are mainly enriched in plasma membrane, extracellular region and MHC class I protein complex, and involved in the interferon signaling pathways, immune response, antigen presentation and cell chemotaxis. The differentially expressed genes associated with chemokines, antigen presentation and vasculogenic mimicry formation were validated by biological experiments. Matrigel matrix-based tube formation assay showed that silencing MAGEA3 in tumor cells impairs tumor vasculogenic mimicry formation. These data indicate that MAGEA3 expression in tumor cells is associated with immune cells infiltration into tumor microenvironment and anti-tumor immune responses, implying that it may play an important role in tumor immune escape. Our findings reveal the potential impact of MAGEA3 on the immunosuppressive tumor microenvironment and will provide promising strategies for improving the efficacy of MAGEA3-targeted immunotherapy.

Triptonide potently suppresses pancreatic cancer cell-mediated vasculogenic mimicry by inhibiting expression of VE-cadherin and chemokine ligand 2 genes

Various aggressive cancers, including pancreatic cancer, produce functional blood vessels by neovascularization. Tumor vasculogenic mimicry (VM) promotes cancer progression and is closely associated with the poor prognosis of the cancer patients. Therefore, tumor VM is a sensible target for novel anti-cancer drug discovery. However, there is a lack of effective anti-tumor VM drugs in the clinical setting. In this study, we aim to explore novel agents to effectually inhibit pancreatic cancer cell-mediated tumor VM for anti-cancer therapy. Pancreatic cancer cell lines Patu8988 and Panc1 were utilized as a model. A mouse model was used for in vitro capillary-like structure formation and in vivo Matrigel plug assays to evaluate the anti-tumor VM efficacy of a small molecule triptonide from traditional Chinese herbs. Various methods, including RT-PCR, immunohistochemical staining, and the luciferase gene transcription reporter system, were applied to study the mechanisms of triptonide-exerted anti-tumor VM. Triptonide effectively inhibited pancreatic cancer cell-formed capillary-like structures in vitro and blood vessels in vivo through suppressing pancreatic cancer cell migration, invasion, and VM via inhibiting expression of tumor VM master gene VE-cadherin and pro-migratory gene chemokine C-X-C motif ligand 2 (CXCL2), mainly via reduction of gene promoter activity. Triptonide potently suppresses pancreatic cancer cell-mediated VM by reducing tumor cell migration and invasion and inhibiting expression of VE-cadherin and CXCL2 genes. Our results provide a novel and potent anti-tumor VM drug candidate for further development of effective anti-pancreatic cancer therapy.

Autophagy-induced KDR/VEGFR-2 activation promotes the formation of vasculogenic mimicry by glioma stem cells

ABSTRACTAntiangiogenesis with bevacizumab, an antibody against vascular endothelial growth factor (VEGF), has been used for devascularization to limit the growth of malignant glioma. However, the benefits are transient due to elusive mechanisms underlying resistance to the antiangiogenic therapy. Glioma stem cells (GSCs) are capable of forming vasculogenic mimicry (VM), an alternative microvascular circulation independent of VEGF-driven angiogenesis. Herein, we report that the formation of VM was promoted by bevacizumab-induced macroautophagy/autophagy in GSCs, which was associated with tumor resistance to antiangiogenic therapy. We established a 3-dimensional collagen scaffold to examine the formation of VM and autophagy by GSCs, and found that rapamycin increased the number of VM and enhanced KDR/VEGFR-2 phosphorylation. Treatment with chloroquine, or knockdown of the autophagy gene ATG5, inhibited the formation of VM and KDR phosphorylation in GSCs. Notably, neutralization of GSCs-produced VEGF with bevacizumab failed to recapitulate the effect of chloroquine treatment and ATG5 knockdown, suggesting that autophagy-promoted formation of VM was independent of tumor cell-derived VEGF. ROS was elevated when autophagy was induced in GSCs and activated KDR phosphorylation through the phosphoinositide 3-kinase (PI3K)-AKT pathway. A ROS inhibitor, N-acetylcysteine, abolished KDR phosphorylation and the formation of VM by GSCs. By examination of the specimens from 95 patients with glioblastoma, we found that ATG5 and p-KDR expression was strongly associated with the density of VM in tumors and poor clinical outcome. Our results thus demonstrate a crucial role of autophagy in the formation of VM by GSCs, which may serve as a therapeutic target in drug-resistant glioma.

Tumor vasculogenic mimicry formation as an unfavorable prognostic indicator in patients with breast cancer.

Vasculogenic mimicry (VM), a newly defined pattern of tumor blood perfusion, describes the functional plasticity of aggressive tumor cells forming de novo vascular networks and is associated with the cancer progression and metastasis. However, the VM-positive rate and the impact of VM status on breast cancer patients’ clinicopathological parameters and prognosis remain unclear. Thus, we performed a meta-analysis by incorporating all available evidence to clarify these issues. Eight studies that involved 1,238 breast cancer patients were eligible for inclusion in our study. We found the VM-positive rate was 24% (pooled proportion was 0.24, 95% CI= 0.13–0.34), and VM was significantly associated with larger tumor size (>2 cm) (OR=0.49, 95% CI=0.26-0.90, P=0.02) and lymph node metastasis (OR=0.27, 95% CI=0.13-0.57, P=0.0005). A boardline correlation was also identified between VM and poorer differentiation (Grade II-III) (OR=0.07, 95% CI=0.00-1.24, P=0.07). Nevertheless, no statistically significant associations were observed between VM and hormone receptor and human epidermal growth factor receptor 2 status. Moreover, the results showed that breast cancer patients with VM-positive have a shorter overall survival than those with VM-negative (HR=0.23, 95% CI=0.08-0.38,P=0.003). In summary, VM was associated with more aggressive tumor phenotype and poor prognosis in patients with breast cancer. Developing strategies against the VM formation would be a promising therapeutic approach to breast cancer.