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 ofα-smooth muscle actin and matrix metalloproteinase-9 in human GBM cell lines at sublethal concentrations.The RNA sequencing data suggested the involvement of the epithelialmesenchymal 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.

ATM Activation is Key in Vasculogenic Mimicry Formation by Glioma Stem-like Cells

Objective Vasculogenic mimicry(VM)is a novel vasculogenic process integral to glioma stem cells(GSCs)in glioblastoma(GBM).However,the relationship between VM and ataxia-telangiectasia mutated(ATM)serine/threonine kinase activation,which confers chemoradiotherapy resistance,remains unclear.Methods We investigated VM formation and phosphorylated ATM(pATM)levels by CD31/GFAPperiodic acid-Schiff dual staining and immunohistochemical staining in 145 GBM specimens.Glioma stem-like cells(GSLCs)derived from the formatted spheres of U87 and U251 cell lines and their pATM level and VM formation ability were examined using western blot and three-dimensional culture.For the examination of the function of pATM in VM formation by GSLCs,ATM knockdown by shRNAs and deactivated via ATM phosphorylation inhibitor KU55933 were studied.Results VM and high pATM expression occurred in 38.5% and 41.8% of tumors,respectively,and were significantly associated with reduced progression-free and overall survival.Patients with VM-positive GBMs exhibited higher pATM levels(r_(s)=0.425,P=0.01).The multivariate analysis established VM as an independent negative prognostic factor(P=0.002).Furthermore,GSLCs expressed high levels of pATM and formed vascular-like networks in vitro.ATM inactivation or knockdown hindered VM-like network formation concomitant with the downregulation of pVEGFR-2,VE-cadherin,and laminin B2.Conclusion VM may predict a poor GBM prognosis and is associated with pATM expression.We propose that pATM promotes VM through extracellular matrix modulation and VE-Cadherin/pVEGFR-2 activation,thereby highlighting ATM activation as a potential target for enhancing anti-angiogenesis therapies for GBM.

Vasculogenic mimicry:a pivotal mechanism contributing to drug resistance in antiangiogenic therapy

The growth of solid tumors relies on establishing a robust blood supply,with angiogenesis playing a key role in this intricate process.Based on this understanding,therapeutic strategies targeting tumor angiogenesis have been developed.However,the clinical effectiveness of antiangiogenic therapy(AAT)in treating tumors has not lived up to expectations.In recent years,vasculogenic mimicry(VM)has attracted increasing attention from the academic community as a longstanding but often overlooked mechanism of nonangiogenic tumor vascularization.Within the tumor microenvironment,neoplastic cells can autonomously form vessel-like structures,creating a blood supply that does not rely on endothelial cells.This phenomenon,known as VM,is a critical marker of aggressive tumors and may play a significant role in conferring resistance to AAT.In this review,we thoroughly examine the evidence,clinical characteristics,and mechanisms of VM across various tumor types and explore its potential role and importance in resistance to AAT and the development of new antitumor therapies.

Pilot Study of Molecular Mechanism on Vasculogenic Mimicry in Bi-directional Differentiated Malignant Tumors

Objective: To investigate the role of collagen IV and PAS positive substancesecreted by tumor cells in vasculogenic mimicry (VM) and the effects of VM on tumor cells expressingVEGF. Methods: 158 cases of bi-direction differential malignant tumor specimens withparaffin-embedded were enrolled into our study and made tissue microarray which were dual-stainedwith CD31-PAS and stained with collagen IV. The difference of the areas and distribution withpattern surrounded by between CD31 and PAS positive respectively were identified via grid-counting,as well as the difference of VEGF expression with VE absent and present. Results: The basementmembrane of VM was both PAS and collagen IV positive. VEGF expression in the bi-directiondifferential malignant tumor was higher VM-absent than VM-present and the difference wasstatistically significance in malignant melanoma and alveolar rhabdomyosarcoma (P 【 0.05).Conclusion: PAS positive substance and collagen IV compose the wall of VE and VE could provide theoxygen and nutrition for tumor growth and progression.

Study on vasculogenic mimicry in malignant esophageal stromal tumors

AIM: To investigate whether malignant esophageal stromal tumors contain PAS-positive patterned matrix-associated vascular channels, which are lined by tumor cells, but not vascular endothelial cells. That is vasculogenic mimicry (VM) independent of tumor angiogenesis. METHODS: Thirty-six tissue samples of malignant esophageal stromal tumors were analyzed. Tissue sections were stained for Vascular endothelial growth factor (VEGF), CD31 and periodic acid Schiff (PAS). The level of VEGF, the microvascular density (MVD) and the vasculogenic mimicry density (VMD) were determined. RESULTS: PAS-positive patterned matrix-associated vascular channels were detected in 33.3% (12/36) of tumor samples. Within these patterned channels, red blood cells were found. The level of VEGF and the MVD in tumors containing patterned channels were significantly higher than those in tumors not containing patterned channels (P < 0.05). At the same time, the malignant degree of tumors was higher, the proportions of tumors containing patterned channels were not only more, but also in the each kind of tumors containing patterned channels. CONCLUSION: In malignant esophageal stromal tumors, a VM mechanism causes some tumor cells to deform themselves and secrete extracellular matrix; thus, PAS-positive patterned matrix-associated vascular channels appear and supplying blood to the tumors to sustain their growth and metastasis.

HIF-1α induces VE-cadherin expression and modulates vasculogenic mimicry in esophageal carcinoma cells

AIM: To investigate whether hypoxia inducible factor (HIF)-1&#x003b1; modulates vasculogenic mimicry (VM) by upregulating VE-cadherin expression in esophageal squamous cell carcinoma (ESCC).

Expression of Maspin in Non-small Cell Lung Cancer and Its Relationship to Vasculogenic Mimicry

Maspin belongs to the serine protease inhibitor （serpin） family and has been proven to be a suppressor of tumor growth and metastasis in many types of tumors. The purpose of this study was to investigate the expression of maspin in non-small cell lung cancer （NSCLC） and its relationship to vasculogenic mimicry （VM）. A total of 160 specimens of NSCLC were involved in this study and 20 specimens of normal lung tissue served as controls. VM, microvessel density （MVD） and the expression of maspin were detected by using immunohistochemical staining. The results showed that the positive rates of maspin and VM in the NSCLC group were 48.1% （77/160） and 36.9% （59/160）, respectively, which were significantly different from those in the control group with the positive rates of maspin and VM being 100% and 0% respectively （P〈0.05）. VM, MVD and the expression level of maspin were significantly related to tumor differentiation, lymph node metastasis, clinical stages and postoperative survival time （all P〈0.05）. The maspin expression in patients with squamous cell carcinoma was significantly higher than that in those with adenocarcinoma （P〈0.05）. The maspin expression was negatively correlated with VM and MVD, and there was a positive correlation between VM and MVD. Maspin-negative expression, VM and high MVD score were negatively related to the 5-year-survival rate. PTNM stages, VM, MVD and maspin expression were independent prognostic factors for NSCLC （P〈0.05）. It was suggested that the loss of expression of maspin may participate in the invasion and metastasis of NSCLC and it has a positive relationship to VM in NSCLC. Combined detection of maspin, VM and MVD may help predict the progression and prognosis of NSCLC.

Vasculogenic Mimicry and Aberrant Expression of HIF-lα/E-cad Are Associated with Worse Prognosis of Esophageal Squamous Cell Carcinoma

Summary： This study aims to find good markers for predicting the prognosis of patients with eso- phageal squamous cell carcinoma （ESCC）. Vasculogenic mimicry （VM） and the expression of hy- poxia inducible factor-1α（HIF-1α）/E-cad protein in ESCC were investigated by immunostaining. The association between VM, HIF-1α/E-cad and clinicopathologic characteristics and 5-year-survival rate of patients with ESCC was analyzed. A total of 160 ESCC specimens were involved in this study and 28 specimens of normal esophageal mucosa served as controls. VM channels were identified in 78 （48.75%） of the 160 ESCC specimens and none of the normal esophageal mucosa was found to have VM. The rates of high-expression of HIF-1αand E-cad in ESCC were 43.75% and 38.75%, while the rates in control were 17.86% and 71.43%, respectively （P〈0.05 for all）. VM and the expression levels of HIF-1α and E-cad were significantly related to lymph node metastasis, serosa infiltration, PTNM staging and 5-year-survival rates of patients with ESCC （P〈0.05 for all）. VM was positively corre- lated with HIF-1α but negatively with E-cad, and HIF-let was negatively correlated with E-cad （P〈0.001 for all）. The 5-year-survival rate of patients with ESCC was 6.41% （5/78） in VM group and 65% （52/82） in non-VM group, 7.14% （5/70） in high HIF-1α expression group and 57.78% （52/90） in low HIF-1α expression group. Oppositely, the 5-year-survival rate in high E-cad expression group was 80.65% （50/62） and that in low E-cad expression group was 7.37% （7/98） （P〈0.05 for all）. Cox multifactor regression analysis indicated that lymph node metastasis, PTNM stage, VM and expres- sion levels of HIF-1α and E-cad were independent risk factors of patients with ESCC （P〈0.05 for all）. Combined detection ofVM, HIF-1α and E-cad plays an important role in predicting the invasion, me- tastasis and prognosis of patients with ESCC.

Notch4 Inhibition Suppresses Invasion and Vasculogenic Mimicry Formation of Hepatocellular Carcinoma Cells

Vasculogenic mimicry（VM） is a process by which aggressive tumor cells generate non-endothelial cell-lined channels in malignant tumors including hepatocellular carcinoma（HCC）. It has provided new insights into tumor behavior and has surfaced as a potential target for drug therapy. The molecular events underlying the process of VM formation are still poorly understood. In this study, we attempted to elucidate the relationship between Notch4 and VM formation in HCC. An effective si RNA lentiviral vector targeting Notch4 was constructed and transfected into Bel7402, a HCC cell line. VM networks were observed with a microscope in a 3 dimensional cell culture system. Cell migration and invasion were evaluated using wound healing and transwell assays. Matrix metalloproteinases（MMPs） activity was detected by gelatin zymography. Furthermore, the role of Notch4 inhibition in Bel7402 cells in vivo was examined in subcutaneous xenograft tumor model of mice. The results showed that downregulation of Notch4 destroyed VM network formation and inhibited migration and invasion of tumor cells in vitro（P〈0.05）. In vivo, tumor growth was also inhibited in subcutaneous xenograft model（P〈0.05）. The potential mechanisms might be related with down-regulation of MT1-MMP, MMP-2, MMP-9 expression and inhibition of the activation of MMP2 and MMP9. These results indicated that Notch4 may play an important role in VM formation and tumor invasion in HCC. Related molecular pathways may be used as novel therapeutic targets for HCC antiangiogenesis therapy.

Downregulation of Astrocyte Elevated Gene-1 Expression Combined with All-Trans Retinoic Acid Inhibits Development of Vasculogenic Mimicry and Angiogenesis in Glioma

Objective This study aimed to investigate the effects of downregulating astrocyte elevated gene-1(AEG-1)expression combined with all-trans retinoic acid(ATRA)on vasculogenic mimicry(VM)formation and angiogenesis in glioma.Methods U87 glioma cells were transfected with AEG-1 shRNA lentiviral vectors(U87-siAEG-1)and incubated in a medium containing 20µmol/L ATRA.Matrigel-based tube formation assay was performed to evaluate VM formation,and the cell counting kit-8(CCK-8)assay was used to analyze the proliferation of glioma cells in vitro.Reverse transcription-quantitative polymerase chain reaction and Western blot analysis were used to investigate the mRNA and protein expression of related genes,respectively.Glioma xenograft models were generated via subcutaneous implantation of glioma cells in nude mice.Tumor-bearing mice received an intraperitoneal injection of ATRA(10 mg/kg per day).Immunohistochemistry was used to evaluate the expression of related genes and the microvessel density(MVD)in glioma xenograft models.CD34/periodic acid-Schiff double staining was performed to detect VM channels in vivo.The volume and weight of tumors were measured,and a tumor growth curve was drawn to evaluate tumor growth.Results A combination of ATRA intervention and downregulation of AEG-1 expression significantly inhibited the proliferation of glioma cells in vitro and glioma VM formation in vitro and in vivo.It also significantly decreased MVD and inhibited tumor growth.Further,the expression levels of matrix metalloproteinase(MMP)-2,MMP-9,vascular endothelial-cadherin(VE-cadherin),and vascular endothelial growth factor(VEGF)in glioma significantly decreased in vivo and in vivo.Conclusion Hence,a combinatorial approach might be effective in treating glioma through regulating MMP-2,MMP-9,VEGF,and VE-cadherin expression.

The effect of alphastatin peptide suppressing the hypoxia-induced vasculogenic mimicry formation of glioma

Objective:To investigate the vasculogenic mimicry formation induced by hypoxia in Ⅱ-Ⅲ human glioma cell and the effect of alphastatin peptide suppressing the hypoxia-induced vasculogenic mimicry formation and the mechanism.Methods:MTT,Transwell and three-dimentional culture were used to detect the proliferation,migration and tubule formation of SHG44.The expression of vascular endothelial growth factor-α(VEGF-α),erythropoietin-producing hepatocellular carcinoma-A2 (EphA2) and matrix metalloproteinases 2 (MMP2) was detected by RT-PCR and Western blotting analysis.Results:The OD 490 in hypoxia group was 0.60±0.06 and in control group was 0.46±0.05.The number of cell migration was 178.71±18.81 in hypoxia group and 85.86±17.92 in control group.The tubule formation was 56.80±12.21 in hypoxia group and 4.20±2.62 in control group.The proliferation,migration and tubule formation in hypoxia group were significantly higher than that in control group.The expression of VEGF-α,EphA2 and MMP2 was upregulated in hypoxia.When various concentrations of alphastatin (100,1 000,10 000 nmol/L) were added to hypoxia group,the numbers of cell migration were 142.57±12.12,92.71±17.68,30.00±7.72 and the tubule formation were 47.71±10.58,18.86±8.40,8.43±5.62.The cell migration and tubule formation were significantly suppressed by alphastatin in a dose-dependent manner.In alphastatin group,the phosphorylation of EphA2 protein (P=0.037,F=4.629) and activation of MMP2 protein (P=0.005,F=9.331) were significantly suppressed but there was no change in VEGF-α protein.Conclusion:Ⅱ-Ⅲ human glioma cell is able to form vasculogenic mimicry induced by hypoxia and alphastatin peptide can suppress the hypoxia-induced vasculogenic mimicry.VEGF-α induced EphA2 phospharilation and MMP2 activation maybe the key pathway to form vasculogenic mimicry.

CircMAN1A2 promotes vasculogenic mimicry of nasopharyngeal carcinoma cells through upregulating ERBB2 via sponging miR-940

Nasopharyngeal carcinoma(NPC)is the most prevalent human primary malignancy of the head and neck,and the presence of vasculogenic mimicry(VM)renders anti-angiogenic therapy ineffective and poorly prognostic.However,the underlying mechanisms are unclear.In the present study,we used miR-940 silencing and overexpression for in vitro NPC cell EdU staining,wound healing assay and 3D cell culture assay,and in vivo xenograft mouse model and VM formation to assess miR-940 function.We found that ectopic miR-940 expression reduced NPC cell proliferation,migration and VM,as well as tumorigenesis in vivo.By bioinformatic analysis,circMAN1A2 was identified as a circRNA that binds to miR-940.Mechanistically,we confirmed that circMAN1A2 acts as a sponge for miR-940,impairs the inhibitory effect of miR-940 on target ERBB2,and then activates the PI3K/AKT/mTOR signaling pathway using RNA-FISH,dual luciferase reporter gene and rescue analysis assays.In addition,upregulation of ERBB2 expression is associated with clinical staging and poor prognosis of NPC.Taken together,the present findings suggest that circMAN1A2 promotes VM formation and progression of NPC through miR-940/ERBB2 axis and further activates the PI3K/AKT/mTOR pathway.Therefore,circMAN1A2 may become a biomarker and therapeutic target for anti-angiogenic therapy in patients with nasopharyngeal carcinoma.

Effect of grape seed proanthocyanidins on tumor vasculogenic mimicry in liver cancer xenograft model

Objective: As a novel blood supply pattern, vasculogenic mimicry(VM) has attracted increasingly attention in recent years, which may partly compensate for the absence of feeding and facilitate tumor perfusion. However, anti-angiogenic drugs have little effect on VM. The grape seed proanthocyanidins(GSPs), a kind of promising bioactive phytochemical, has shown anti-carcinogenesis and anti-angiogenic in several tumor models. However, GSPs regulation of VM and its possible mechanisms in a H22 hepatoma carcinoma model remain not clear. The aim of this study was to examine the effects of GSPs on proliferation and VM in a H22 hepatoma carcinoma model and to investigate the underlying mechanism. Methods: Seventy-five mice were divided into the control group and experimental groups treated with different concentration of GSPs. CD34-PAS dual staining was employed to identify the VM structure. The immunohistochemical staining for investigating the expression of VEGF, Eph A2 and MMP-2 protein was performed. Results: Treatment of the H22 model with Endostar(4 mg/kg), 50, 100, 200 mg/kg of the GSPs resulted in 6.87%, 17.81%, 27.43%, 53.52% inhibition in tumor growth, respectively. The mean weight of tumors were significantly lower in GSPs(100 mg/kg) and GSPs(200 mg/kg) groups than in the control group(all P < 0.01). Similarly, compared with the control group, the number of VM channels were significantly reduced in GSPs(100 mg/kg) and GSPs(200 mg/kg) groups(all P < 0.01). Immunohistochemistry showed significant decreases in the expression levels of VEGF, Eph A2 and MMP-2 protein in GSPs(100 mg/kg) and GSPs(200 mg/kg) groups when compared with control group(all P < 0.001). Conclusion: This is the first report providing evidence that GSPs inhibit the VM structure by regulation of the VEGF/Eph A2/MMPs signaling pathway. Therefore, we concluded that GSPs has the potential of being a clinical anti-VM inhibitor.

Vasculogenic mimicry in non-small cell lung cancer and its relationship with tumor stage

Objective： The purpose of the study was to study the mechanism of vasculogenic mimicry （VM） and its relationship with tumor stage in non-small cell lung cancer （NSCLC）. Methods： Forty-two patients with NSCLC were collected, 19 belonged to the early stage （stages Ⅰ ＋Ⅱ） while 23 were late stage （stages Ⅲ ＋ Ⅳ）. Moreover, 20 patients got surgical treat ment and 22 got chemotherapy. We studied the relationship of VM with stage, chemotherapeutic effect, HIF-la, microves sel density （MVD） and clinicopathologic features. Results： VM in patients of early stages were significantly more than late stages （68.4% vs 26.1%, P = 0.006）, and the positive rate of VM was proportional to HIF-la （P = 0.034）. But no correlation was found between VM and chemotherapeutic effect （14.3% vs 26.7%, P = 1.00） or MVD （P 〉 0.05）. Furthermore, we found VM also showed a negative correlation with distant metastases and lymph nodes metastases （P 〈 0.05） while no correlation was found with other clinicopathologic. Conclusion： VM was generated during the early stage in NSCLC and correlated with lymph nodes metastases. As the disease progressed, VM may be replaced by vascular endothelial cells, so the late-stage patients especially people with distant metastases had fewer VM. As the main factor produced by hypoxia, HIF-la may make a difference in VM formation. Thus we inferred VM might be a new target for targeted therapy, and could provide help for clinical staging and treatment.

Vasculogenic mimicry formation in hepatocellular carcinoma

Objective： To explore possibility of vasculogenic mimicry （VM） in hepatocellular carcinoma （HCC） by constructing tumor cell three-dimensional culture system and liver cancer tissues. Methods： Based on three-dimensional cell culture system developed by matrigel, liver cancer cell lines HepG2 were tested for evidence of VM. Fifteen HCC simples were collected. Potential formation of tumor channels and their characterization of network were observed by immunohistochemical and histological double staining of CD31 and PAS, or Ferritin and PAS. Results： Three-dimensional culture model of HCC cell line proved the liver cancer cells stretch out thin and long tubers at the second day, and the cells linked each other to form wreath and network structure at the seventh day. In fifteen HCC simples, endothelial cells were all stained by CD31, and tumor cells were all stained by Ferritin. The immunohistochemical and histological double staining also exhibited evidence of VM in seven simples of HCC, CD31-negative and Ferritin-positive tumor cells were observed to form tubal structure. Tumor cells were separated by PAS-positive matter like basement membrane from the tube. Red blood cells could be seen in the tube. In well-differentiated simples, VM was less than that in poorly differentiated ones, and several CD31-positive tumor cells could be observed in poorly differentiated simples. Conclusion： HepG2 cells have the capacity of self-metamorphose and vascularized trend. The tumor cells can obtain oxygen and nutrition through this structure.

Expression of HIF-1α in hepatocellular carcinoma and its relationship with vasculogenic mimicry and clinical pathology

Objective： The aim of this study was to discuss HIF-la expression and vasculogenic mimicry （VM） in hepatocel- lular carcinoma （HCC） and their relationship with the clinical pathological features and clinical significance. Methods： Two hundred and seven specimens from patients in The Affiliated Hospital of North Sichuan Medical College who received hepatic cell carcinoma resection were tested by immunohistochemistry and double staining of CD31 and PSA. Then detected the expression of HIF-la, VM, and analysed the relationship between clinical pathology. Results： The HIF-la positive rate was 71.01% and its expression was associated with liver cirrhosis, tumor size and TNM stage （P 〈 0.05）. HIF-la protein expres- sion was positively associated with the VM （y = 0.1988, P = 0.0041）. Conclusion： Hypoxia may be the reason for VM in high invasive HCC, regulating the tumor microenvironment may have great significance in inhibiting invasion and metastasis of HCC.

Effects of Vasculogenic Mimicry on Postoperative Recurrence and Progression of Non-Small Cell Lung Cancer

Vasculogenic mimicry(VM)in lung cancer shortens overall survival(OS)but its'associations with postoperative recurrence and progression of early non-small cell lung cancer(NSCLC)remain unclear.The purpose of this study was to analyze the association of VM with postoperative recurrence and progression of NSCLC as well as the effect of VM on postoperative recurrence-free survival(RFS).This study included NSCLC patients and detected VM in surgical specimens.The associations ofVM with the recurrence and progression were analyzed to assess the effect ofVM on postoperative RFS in NSCLC.A total of 80 NSCLC cases were followed up for 3 years.During follow-up,35 cases showed recurrence and progression where 5(6.25%)cases had simple local recurrence and the other 30(37.5%)cases had distant metastasis.The recurrence and progression rates in the first,second,and third years were 12.50%,23.75%,and 7.50%,respectively.The median RFS was 14.2 months.VM was detected in 30 out of 80 cases and was significantly correlated with tumor differentiation(r=0.365)and clinical stage(r=0.374)(both,P=0.001).Local recurrence of NSCLC was not correlated with VM,unlike distant metastasis(r=0.598,P<0.001).Average RFS was significantly longer in NSCLC patients without VM compared with the VM group 3 years post-operation(32 months versus 18 months,log-rank test P<0.001).Considering these,VM is significantly correlated with postoperative distant metastasis of NSCLC in which it is of a certain value for predicting poor prognosis in NSCLC.

Vasculogenic Mimicry and Its Molecules Signaling Pathways

Tumors require a blood supply for growth and hematogenous metastases. Until recently, mast research in this field has focused on the role of angiogenesis, the recruitment of new yes,As into a tumor from preexisting vessels. The warn vaseulogenic mimicry describes the formation of fluld-condueting channels by highly invasive and genetically dysregulated tumor cells. Vaseulogenie mimicry provides an opportunity to investigate the interrelationships between the genetically dysregulated invasive tumor cell, the microenvironment, and the malignant switch. This artide is purposed to present the models and the molecule mechanisms of tumor vasculogenie mimicry.

DPY19L3 promotes vasculogenicmimicry by its C-mannosyltransferase activity

C-mannosylation is a post-translational modification that occurs intracellularly in the endoplasmic reticulum.In humans,biosynthesis of C-mannosylation in proteins containing thrombospondin type 1 repeat is catalyzed by the DPY19 family;nonetheless,biological functions of protein C-mannosylation are not yet fully understood,especially in tumor progression.Vasculogenic mimicry(VM)is the formation of fluid-conducting channels by highly invasive and genetically deregulated tumor cells,enabling the tumors to form matrix-embedded vasculogenic structures,containing plasma and blood cells to meet the metabolic demands of rapidly growing tumors.In this study,we focused on DPY19L3,a C-mannosyltransferase,and aimed to unravel its role in VM.Knockout of DPY19L3 inhibited the formation of VM in HT1080 human fibrosarcoma cells.Re-expression of wild-type DPY19L3 recovered VM formation;however,DPY19L3 isoform2,an enzymatic activity-defect mutant,did not restore it,suggesting that the C-mannosyltransferase activity of DPY19L3 is crucial to its function.Furthermore,the knockdown of DPY19L3 in MDA-MB-231 breast cancer cells hindered its network formation ability.Altogether,our findings suggest that DPY19L3 is required for VM formation and stipulate the relevance of C-mannosylation in oncogenesis.

Contribution of cancer stem cells to tumor vasculogenic mimicry

Vasculogenic mimicry(VM),a newly-defined pattern of tumor blood supply,provides a special passage without endothelial cells and is conspicuously different from angiogenesis and vasculogenesis.The biological features of the tumor cells that form VM remain unknown.Cancer stem cells(CSCs)are believed to be tumorinitiating cells,capable of self-renewal and multipotent differentiation,which resemble normal stem cells in phenotype and function.Recently CSCs have been shown to contribute to VM formation as well as angiogenesis.These findings challenge the previous understanding of the cellular basis of VM formation.In this review,we present evidence for participation of CSCs in VM formation.We also discuss the potential mechanisms and possible interaction of CSCs with various elements in tumor microenvironment niche.Based on the importance of VM in tumor progression,it constitutes a novel therapeutic target for cancer.