The involvement of Notch signaling in melanoma vasculogenic mimicry

Notch signaling plays an important role in tumor angiogenesis. Recent studies suggest that Notch signaling also regulates the progression of primary melanomas toward an aggressive phenotype. The aim of this study was to investigate the involvement of Notch signaling pathway in organization of tumor cells into capillary-like structures (CLS), the phenomenon also known as vasculogenic mimicry (VM). Here, we show that Notch signaling cascade was constitutively active in melanoma cell lines we used. Blocking Notch signaling with the γ-secretase inhibitors, DAPT, dibenzazepine or Jagged1 neutralizing antibody resulted in stabilization of CLS indicating that Notch signaling pathway attenuates melanoma VM. We further studied this phenomenon on melanomas grafted in nude mice. Compared to control, VM channels in DAPT-treated grafted melanoma became larger and more branched. DAPT-treated melanomas also exhibited an up-regulation of MMP-2 and VEGFR1, both known as VM mediators. Moreover, we did not observe necrosis in VM channels areas of DAPT-treated melanomas. These findings indicate that VM regulated by Notch signaling may present a novel target in melanoma therapy.     

Endothelin-1 induces the transactivation of vascular endothelial growth factor receptor-3 and modulates cell migration and vasculogenic mimicry in melanoma cells

Endothelin receptor B (ET_BR) is a G-protein-coupled receptor overexpressed in melanoma, blood, and lymphatic endothelial cells. Given that aberrant signal transduction can be mediated through cross talk between receptors, here, we explore the functional relationship between ET_BR and the vascular endothelial growth factor receptor (VEGFR)-3 system and how this cross talk might influence the aggressive behavior of melanoma cells. The expression of VEGFR-3 and its ligands, VEGF-C and VEGF-D, significantly increased after activating ET_BR by ET-1 in primary and metastatic melanoma cell lines. These effects, similarly to those induced by hypoxia, were mediated by hypoxia-inducible factor (HIF)-1α and HIF-2α. ET-1 caused the phosphorylation of VEGFR-3, which was accompanied by the activation of the downstream signaling molecules, such as MAPK and AKT. Inhibition of c-Src activity or silencing of the scaffold protein β-arrestin-1 reduced ET-1-induced VEGFR-3 phosphorylation, demonstrating that, upon ET-1 stimulus, β-arrestin-1 is involved with c-Src in the ET_BR-mediated VEGFR-3 transactivation. Moreover, ET-1 in combination with VEGF-C further increased VEGFR-3, MAPK, and AKT phosphorylation and markedly promoted cell migration and vasculogenic mimicry. Dual inhibition of ET_BR and VEGFR-3 was required for the effective inhibition of these effects, as well as for VEGFR-3 phosphorylation, demonstrating that ET_BR cross talk with VEGFR-3 enhances cell plasticity and motility. Finally, in melanoma xenografts, ET_BR antagonist inhibited tumor growth and the activation of the VEGF-C/VEGFR-3 axis, indicating that targeting ET_BR may improve melanoma treatment acting directly or indirectly by impairing ET_BR cross talk with VEGFR-3.     

Caspase家族在肿瘤血管生成拟态形成过程中的作用

目的探讨凋亡相关蛋白Caspase-3及其上游的Caspase-8、Caspase-9在肿瘤血管生成拟态(vasculogenic mimicry,VM)中的作用。方法建立C57BL小鼠B16恶性黑色素移植瘤模型,并随机分为Caspase-3抑制剂组、Caspase-8和Caspase-9抑制剂联合用药组、对照组,待成瘤后每日分别注射Caspase-3、Caspase-8、Caspase-9抑制剂,记录肿瘤体积并绘制肿瘤生长曲线。通过免疫组化-PAS双染法检测并计数各组肿瘤组织VM的形成数目;通过明胶酶谱法检测肿瘤组织中MMP-2和MMP-9的活性。结果与对照组相比,Caspase-3抑制剂组和Caspase-8、Caspase-9抑制剂联合用药组肿瘤体积的生长速度较缓慢,差异有统计学意义(P<0.05),Caspase-3抑制剂组和Caspase-8、Caspase-9抑制剂联合用药组肿瘤组织中VM的数量小于对照组,差异有统计学意义(P<0.05),对照组MMP-2、MMP-9的活性强于Caspase-3抑制剂组,差异有统计学意义(P<0.05),对照组MMP-9的活性强于Caspase-8、Caspase...     

Tumor cell plasticity in uveal melanoma: microenvironment directed dampening of the invasive and metastatic genotype and phenotype accompanies the generation of vasculogenic mimicry patterns

The histological detection of laminin-rich vasculogenic mimicry patterns in human primary uveal melanomas is associated with death from metastases. We therefore hypothesized that highly invasive uveal melanoma cells forming vasculogenic mimicry patterns after exposure to a laminin-rich three-dimensional microenvironment would differentially express genes associated with invasive and metastatic behavior. However, we discovered that genes associated with differentiation (GDF15 and ATF3) and suppression of proliferation (CDKNa1/p21) were up-regulated in highly invasive uveal melanoma cells forming vasculogenic mimicry patterns, and genes associated with promotion of invasive and metastatic behavior such as CD44, CCNE2 (cyclin E2), THBS1 (thrombospondin 1), and CSPG2 (chondroitin sulfate proteoglycan; versican) were down-regulated. After forming vasculogenic mimicry patterns, uveal melanoma cells invaded only short distances, failed to replicate, and changed morphologically from the invasive epithelioid to the indolent spindle A phenotype. In human tissue samples, uveal melanoma cells within vasculogenic mimicry patterns assumed the spindle A morphology, and the expression of Ki67 was significantly reduced in adjacent melanoma cells. Thus, the generation of vasculogenic mimicry patterns is accompanied by dampening of the invasive and metastatic uveal melanoma genotype and phenotype and underscores the plasticity of these cells in response to cues from the microenvironment.     

CD133和CD34在肝细胞癌血管生成拟态形成中的表达及意义

背景：在恶性肿瘤中血管生成拟态的形成过程与肿瘤干细胞有密切联系。 目的：分析肝癌干细胞标志物CD133和CD34在肝细胞癌血管生成拟态形成中的表达及意义。 方法：建立肝癌细胞HCC97H、SMMC7721和正常肝细胞L02三维培养体系,结合激光捕获显微切割技术分离形成血管生成拟态的肝癌细胞,分别利用RT-PCR和Western blot技术检测CD133和CD34表达水平。 结果与结论：三维培养条件下,肝癌细胞HCC97H细胞形成血管生成拟态,肝癌细胞SMMC7721以及正常肝细胞L02未形成血管生成拟态。形成血管生成拟态的肝癌细胞HCC97H中CD133、CD34在mRNA及蛋白表达水平上均高于未形成血管生成拟态的肝癌细胞SMMC7721和正常肝细胞L02(P < 0.05)。表明高侵袭性肝癌细胞在三维培养下形成血管生成拟态,而低侵袭性肝癌细胞及正常肝细胞不能形成血管生成拟态;肝癌细胞形成血管生成拟态的过程中与表达肝癌干细胞有关。     

Caveolin-1 promotes tumor cell proliferation and vasculogenic mimicry formation in human glioma

Vasculogenic mimicry (VM) plays an important role in human glioma progression and resistance to antiangiogenic therapy as a compensatory neovascularization mechanism in malignant tumors. Caveolin-1 (Cav-1) has been found to contribute to VM formation. However, it remains largely unknown whether Cav-1 expression correlates with VM in glioma. In this study, we examined CAV-1 expression levels and VM in human glioma cell lines and in 94 human gliomas with different grades of malignancy, and present Cox proportional hazards regression. The molecular role of Cav-1 in glioma cells was investigated using quantitative polymerase chain reaction (qRT-PCR) assays, western blotting, CCK-8 assays, and tubule formation assays. Cav-1 expression and VM formation were positively correlated with each other and both were closely associated with glioma development and progression as evidenced by the presence of cystic tumor, shortened survival time, and advanced-stage glioma in glioma patients with Cav-1 overexpression/increased VM formation. Cav-1 promoted U251 glioma cell proliferation and VM formation in a Matrigel-based 3D culture model. VM-associated factors including hypoxia-inducible factor 1α (HIF-1α) and p-Akt was significantly elevated by Cav-1 overexpression but suppressed by siCav-1 in U251 cells. Collectively, our study identified Cav-1 as an important regulator of glioma cell proliferation and VM formation, contributing to glioma development and progression.     

Demonstration of vasculogenic mimicry in astrocytomas and effects of Endostar on U251 cells

Angiogenesis is an important process for the cell growth of normal and tumor tissues. Vasculogenic mimicry (VM) is a newly described vascular network structure that was first described in aggressive melanomas. To find out whether VM also exists in astrocytomas and to examine its clinical significance, we studied 80 malignant astrocytoma samples using immunohistochemistry coupled with periodic acid-Schiff (PAS) staining. To explore the possible therapeutic methods of anti-VM formation, we cultured astrocytoma cells using three-dimensional Matrigel and investigated the effects of Endostar, an endothelial cell growth inhibitor, on astrocytoma cell growth, invasion, and VM formation. VM structures were found in 8 samples of malignant astrocytomas, seven of which were grade IV astrocytomas. Glioblastoma U251 cells cultured in Matrigel formed vessel-like loops and networks, mimicking the features of VM in vivo, whereas such structures were not found in cultured normal astrocytes or well-differentiated astrocytoma SHG44 cells. In addition, treatment with Endostar led to a dose- and time-dependent inhibition of proliferation and invasion of both U251and SHG44 cells, but VM formation by U251 cells in vitro was not prominently affected. In conclusion, VM is frequently detected in aggressive glioblastomas, and the presence of VM may constitute a new predictor for poor prognosis in astrocytoma patients. Although Endostar has broad anti-tumor effects due to anti-angiogenesis and anti-tumor cell mechanisms, its inhibitory effects on VM formation by U251cells in vitro are not remarkable.     

Association of Notch1 with vasculogenic mimicry in human hepatocellular carcinoma cell lines

Background and aims: According to recent findings, some tumor cells function as endothelial progenitor cells to initiate tumor vasculogenesis, known as “vasculogenic mimicry” (VM). Notch1, the key regulator of vasculogenesis and embryonic differentiation, has shown a correlation with a poor prognosis in hepatocellular carcinoma (HCC). We attempted to elucidate the relationship between Notch1 and the vascularization of HCC. Materials and methods: HCC cell lines were assayed for tube formation and low-density lipoprotein (LDL) absorption. The translation level of targets of interest was verified using western blot. Notch1 was silenced in HepG2, BEL-7402 and HCCLM6 using lentivirus shRNA. A hypoxic culture was conducted in an anaerobic culture chamber to induce VM in HepG2. Samples from 53 patients with HCC, i.e., 5 with metastasis and 48 without were tested for Notch1⁺ cells and CD34 negative plus Periodic Acid-Schiff (PAS) positive structures, respectively. Results: BEL-7402 and HCCLM6 were capable of tube formation and LDL absorption in vitro, while HepG2 was negative for both. Notch1 down-regulation suppressed endothelial marker expression and greatly impaired tube formation. After hypoxic culture, the tube formation capacity of HepG2 was significantly enhanced, along with an increase in Notch1 expression. Notch1 was strongly and profusely expressed in all 5 cases of distant metastasis, while 19 of the 48 cases without metastasis were sparsely positive (P < 0.05). Notch1 positivity was mainly seen in the cytoplasm and nuclei. VM structures were only found in 2 cases from the metastasis group (P < 0.05). Conclusions: HCC is capable of VM. Notch1 might serve as a potential target for VM development in HCC.     

Role and mechanism of vasculogenic mimicry in gastrointestinal stromal tumors

Vasculogenic mimicry (VM) is the formation of fluid-conducting channels by highly invasive and genetically dysregulated tumor cells. In this study, we collected specimens of 84 human gastrointestinal stromal tumors (GISTs) along with clinicopathologic data and another 42 GISTs with fresh tissue that was used for gelatin zymography. VM was found in 21 of the 84 GISTs using CD31/periodic acid-Schiff double staining and CD117 and CD31 immunohistochemical staining. There was a significant difference in the VM-positive rate between the lesions with a mitotic rate > or =5/50 high-power fields and those with a lower mitotic rate (P = .000) and between the cases with and without liver metastasis (P = .008). There was a significant difference in the VM-positive rate between the high-risk group (5.9%) and the very low/low-risk group (12.5%) (P = .010) or the intermediate-risk group (39.5%) (P = .020). Kaplan-Meier survival analysis showed VM indicated a poor prognosis (P = .0000). Cox proportional hazards model indicated that the presence of VM, tumor size 10 cm or greater, and hemorrhage were independent predictors of a poor prognosis (P = .000, .005, .032, respectively). The staining indexes of matrix metalloproteinase (MMP)-2 and MMP-9 were higher in the VM-positive than in the VM-negative group (P = .024 and .037, respectively). Gelatin zymography showed that the activity of MMP-2 and MMP-9 was significantly higher in the VM-positive lesions (P = .013 and .033, respectively). We conclude that VM in GISTs is an unfavorable prognostic sign and that patients with VM-positive tumors are prone to suffer liver metastasis. Both MMP-2 and MMP-9 play an important role in VM formation in GISTs.     

Deciphering the signaling events that promote melanoma tumor cell vasculogenic mimicry and their link to embryonic vasculogenesis: Role of the Eph receptors

During embryogenesis, the primordial microcirculation is formed through a process known as vasculogenesis. The term “vasculogenic mimicry” has been used to describe the manner in which highly aggressive, but not poorly aggressive melanoma tumor cells express endothelial and epithelial markers and form vasculogenic‐like networks similar to embryonic vasculogenesis. Vasculogenic mimicry is one example of the remarkable plasticity demonstrated by aggressive melanoma cells and suggests that these cells have acquired an embryonic‐like phenotype. Since the initial discovery of tumor cell vasculogenic mimicry by our laboratory, we have been focusing on understanding the molecular mechanisms that regulate this process. This review will highlight recent findings identifying key signal transduction events that regulate melanoma vasculogenic mimicry and their similarity to the signal transduction events responsible for promoting embryonic vasculogenesis and angiogenesis. Specifically, this review will focus on the role of the Eph receptors and ligands in embryonic vasculogenesis, angiogenesis, and vasculogenic mimicry. Developmental Dynamics 236:3283–3296, 2007. © 2007 Wiley‐Liss, Inc.     

B16-F10 melanoma cells contribute to the new formation of blood vessels in the chick embryo chorioallantoic membrane through vasculogenic mimicry

Grafting of mammalian cells and tissues to the chick embryo chorioallantoic membrane (CAM) is a well-established experimental system to evaluate many different parameters of tumor growth, and B16-F10 murine melanoma cell line has been successfully used to study metastatic process in the CAM assay. The aim of this study was to demonstrate the capability of B16-F10 melanoma cells to contribute to the new formation of host blood vessels through a vasculogenic mimicry mode. Results have shown that B16-F10 melanoma cells are able to form in 4 days macroscopic tumor masses and induce a strong angiogenic response comparable to that of a well-known angiogenic cytokine, namely fibroblast growth factor-2. Moreover, tumor cells are able to cross the chorionic epithelium, and to move beneath in the mesenchyme to form tumor masses immunoreactive to specific antibodies anti-S100 and anti-MART-1/Melan-A. Finally, we have shown that CAMs new-formed blood vessels are lined by both pigmented melanoma cells and cells immunoreactive to MART-1/Melan-A and PAS, suggesting the occurrence of a vasculogenic mimicry process.     

Galectin-3 expression in various thyroid neoplasms and its possible role in metastasis formation

Galectin-3 is a member of the beta-galactoside-binding protein family that plays an important role in cell-cell adhesion and in cell-matrix interaction. We have examined the expression of galectin-3 in normal, adenomatous, and malignant thyroid tissues and also in metastatic lesions. Galectin-3 was rarely expressed in normal thyroid tissue but was abundant in the cytoplasm of the neoplastic lesions. Among neoplastic lesions, galectin-3 was expressed to a greater extent in follicular carcinomas than in follicular adenomas and was present in greater amounts in papillary carcinomas than in follicular adenomas or carcinomas. Primary lesions of papillary carcinoma with metastasis contained significantly higher concentrations of galectin-3 than tumors of this type without metastases. However, the expression of galectin-3 was significantly decreased in metastatic lesions in the lymph nodes compared with their primary lesions. From these results, we assumed that galectin-3 works in different ways at different stages of thyroid neoplasm proliferation. Among primary tumors, galectin-3 expression is significantly different in 3 histological types. However, the continuity of progression among these tumors is not yet proven. In later stages, decreased expression of galectin-3 may aid the release of cancer cells from the primary lesions for invasion and metastasis.     

铁对三阴性乳腺癌细胞体外血管生成拟态的影响

目的研究铁对三阴性乳腺癌细胞体外血管生成拟态(VM)的影响及其机制。方法将细胞分为6组:对照组、30和300μmol/L含羞草氨酸组、500μmol/L去铁胺组及50和500μmol/L乳酸亚铁组。用MTT法检测细胞增殖活力,三维培养和PAS染色鉴定细胞形成VM的能力,免疫荧光染色法检测ROS变化,Western blot检测p-ERK1/2表达。结果去铁胺、含羞草氨酸均可显著抑制血管样结构形成(P0.05),乳酸亚铁可促进其形成(P0.05),并且血管样结构表现为PAS染色阳性。细胞血管样结构形成能力与胞内ROS及p-ERK1/2表达水平变化相一致。加入PD98059可以显著抑制其形成(P0.05)。结论铁诱导生成ROS促进VM的形成,ERK1/2的异常激活可能是主要调节机制。     

Expression Pattern and Immunoregulatory Roles of Galectin-1 and Galectin-3 in Atopic Dermatitis and Psoriasis

Inflammation - The pathogenesis of atopic dermatitis (AD) and psoriasis (Ps) overlaps, particularly the activation of the immune response and tissue damage. Here, we evaluated galectin (Gal)-1 and...     

口虾蛄提取物对人鼻咽癌细胞迁移和体外血管生成拟态的抑制作用

 目的：研究口虾蛄提取物（extract of Oratosquilla,EOS）对人低分化鼻咽癌细胞株CNE-2的迁移及体外血管生成拟态的影响。方法：用不同浓度（0 mg/L 、125 mg/L、250 mg/L、500 mg/L）EOS处理CNE-2细胞24 h后,创伤修复实验检测细胞迁移能力;通过Matrigel三维细胞培养观察CNE-2细胞形成类血管网状结构的能力及其特点;体外管道形成抑制实验检测不同浓度EOS对CNE-2细胞管道形成能力的影响;Western blotting法检测不同浓度EOS对CNE-2细胞fascin 1和血管内皮生长因子（VEGF）蛋白表达的影响。结果：EOS可以显著降低CNE-2细胞的迁移能力,与对照组比较差异有统计学意义（P＜0.01）;CNE-2细胞在Matrigel上培养能形成类似血管的网状样结构;EOS能以剂量依赖方式抑制CNE-2细胞体外管道形成的数量（P＜0.01）;EOS能抑制CNE-2细胞中fascin 1和VEGF蛋白的表达（P＜0.01）,且其管状结构数量与2种蛋白变化趋势呈正相关（P＜0.05）。结论：CNE-2细胞具有血管生成拟态的能力;EOS能够抑制CNE-2细胞的迁移和体外血管生成拟态的能力,其机制可能与下调fascin 1和VEGF蛋白的表达有关。     

The plasticity of human Treg and Th17 cells and its role in autoimmunity

CD4⁺ T helper cells are a central element of the adaptive immune system. They protect the organism against a wide range of pathogens and are able to initiate and control many immune reactions in combination with other cells of the adaptive and the innate immune system. Starting from a naive cell, CD4⁺ T cells can differentiate into various effector cell populations with specialized function. This subset specific differentiation depends on numerous signals and the strength of stimulation. However, recent data have shown that differentiated CD4⁺ T cell subpopulations display a high grade of plasticity and that their initial differentiation is not an endpoint of T cell development. In particular, FoxP3⁺ regulatory T cells (Treg) and Th17 effector T cells demonstrate a high grade of plasticity, which allow a functional adaptation to various physiological situations during an immune response. However, the plasticity of Treg and Th17 cells might also be a critical factor for autoimmune disease. Here we discuss the recent developments in CD4⁺ T cell plasticity with a focus on Treg and Th17 cells and its role in human autoimmune disease, in particular multiple sclerosis (MS).     

Formation of vasculogenic mimicry in bone metastasis of prostate cancer: Correlation with cell apoptosis and senescence regulation pathways

Vasculogenic mimicry (VM) has been found in prostate cancer (PCa) as an independent marker of poor prognosis. To investigate the correlation between VM and bone metastasis in PCa, a total of 80 cases were analyzed by CD31 and PAS dual-staining as well as the follow-up data. All cases were divided into two groups: VM-positive and VM-negative (VM-pos/VM-neg). Immunohistochemical staining for investigating the expression of Casepase-3, Bcl-2/Bax, and SA-β-gal was performed. 28 of the 80 PCa cases exhibited VM structure (35.0%). The incidence of bone metastasis in the VM-pos and VM-neg was 67.9% (19/28) and 38.5% (20/52), respectively. The positive rate of Casepase-3 and Bcl-2 expression was significantly different of the two groups (Caspases-3: VM-pos 71.4%, 20/28 vs VM-neg 42.3%, 22/52; Bcl-2: VM-pos 35.7%, 10/28 vs VM-neg 65.4%, 34/52). Bcl-2/Bax ratio of the VM-pos (0.71 ± 0.22) was lower than that of the VM-pos (0.89 ± 0.13). In addition, a higher frequency of SA-β-gal was detected in VM-pos (64.29 ± 86.42) than in VM-neg (25.37 ± 72.21). Taken together, our findings demonstrate that PCa with VM has the tendency to develop bone metastasis. Activations of cell apoptosis and senescence regulation pathways may play important roles in the formation process of VM structure.     

胃腺癌血管生成拟态的形态学观察和MMP-2表达

目的研究胃腺癌中是否存在血管生成拟态(vasculogenic mimicry,VM)及其与MMP-2表达的关系,以及MMP-2表达的临床意义。方法收集121例胃腺癌标本及临床病例资料,利用CD34和PAS双重染色观察是否存在VM,然后对存在VM组和对照组进行MMP-2染色,分析VM与MMP-2表达的关系以及MMP-2表达与患者临床病理指标的关系。结果 121例胃腺癌中有44例(36.36%)存在VM。有VM组的MMP-2高表达的比例明显高于无VM组,两组之间的差异有统计学意义(P0.01)。伴有淋巴结转移的胃癌组织MMP-2高表达的比例显著高于无淋巴结转移的胃癌组织(P0.05)。结论胃腺癌中存在VM,MMP-2的高表达可能与VM形成及肿瘤淋巴结转移有关。