Levels of soluble vascular endothelial growth factor (VEGF) receptor 1 in astrocytic tumors and its relation to malignancy, vascularity, and VEGF-A.

PURPOSE: Vascular endothelial growth factor (VEGF)-A isa key mediator of angiogenesis in malignant gliomas. Soluble VEGF receptor 1 (sVEGFR-1) can complex VEGF-A and reduce its bioavailability. In several animal models sVEGFR-1 inhibited angiogenesis and tumor growth. We analyzed the levels of endogenous sVEGFR-1 in gliomas of different malignancy grades in relation to tumor vascularity and VEGF-A. EXPERIMENTAL DESIGN: The concentration of sVEGFR-1 was determined by ELISA in 104 gliomas and normal brain. Levels of sVEGFR-1 were compared with malignancy grade, microvessel density, and VEGF-A concentration. Effects of sVEGFR-1 on glioma extract-induced endothelial cell chemotaxis were analyzed in vitro. RESULTS: The concentration of sVEGFR-1 correlated with the malignancy grade and was 12-fold higher in glioblastomas than in diffuse astrocytomas (P < 0.001), with intermediate levels for anaplastic astrocytomas. VEGF-A levels were 30-fold higher (P < 0.001) in glioblastomas than in diffuse astrocytomas. The sVEGFR-1:VEGF-A ratio was 0.27 in glioblastomas and 0.70 in diffuse astrocytomas. Both sVEGFR-1 and VEGF-A correlated with microvessel density (P < 0.001) and with each other (P < 0.001); sVEGFR-1 and VEGF-A also correlated with each other when only glioblastomas were analyzed (P = 0.001). In vitro, recombinant sVEGFR-1 inhibited endothelial cell chemotaxis induced by tumor extracts. CONCLUSIONS: Although absolute levels of sVEGFR-1 are increased in the more malignant gliomas, the sVEGFR-1:VEGF-A ratio is decreased 2.6-fold in glioblastomas compared with diffuse astrocytomas, suggesting that the ensuing increased bioavailability of VEGF-A favors angiogenesis. The inhibition of tumor extract-induced endothelial chemotaxis by sVEGFR-1 suggests that sVEGFR-1 could be useful as an angiogenesis inhibitor in the specific context of human gliomas.     

Heme oxygenase-1 expression in human gliomas and its correlation with poor prognosis in patients with astrocytoma

In human glioma tumors, heme oxygenase-1 (HO-1) has been shown to be upregulated both when compared with normal brain tissues and also during oligodendroglioma progression. The cell types that express HO-1 have been shown to be mainly macrophages/microglia and T cells. However, many other reports also demonstrated that cell lines derived from glioma tumors and astrocytes express HO-1 after the occurrence of a wide variety of cell injuries and stressors. In addition, the significance of HO-1 upregulation in glioma had not, so far, been addressed. We therefore aimed at investigating the expression and significance of HO-1 in human glial tumors. For this purpose, we performed a wide screening of HO-1 expression in gliomas by using tissue microarrays containing astrocytomas, oligodendrogliomas, mixed tumors, and normal brain tissues. We subsequently correlated protein expression with patient clinicopathological data. We found differences in HO-1 positivity rates between non-malignant brain (22 %) and gliomas (54 %, p?=?0.01). HO-1 was expressed by tumor cells and showed cytoplasmic localization, although 19 % of tumor samples also depicted nuclear staining. Importantly, a significant decrease in the overall survival time of grade II and III astrocytoma patients with HO-1 expression was observed. This result was validated at the mRNA level in a cohort of 105 samples. However, no association of HO-1 nuclear localization with patient survival was detected. In vitro experiments aimed at investigating the role of HO-1 in glioma progression showed that HO-1 modulates glioma cell proliferation, but has no effects on cellular migration. In conclusion, our results corroborate the higher frequency of HO-1 protein expression in gliomas than in normal brain, demonstrate that HO-1 is expressed by glial malignant cells, and show an association of HO-1 expression with patients’ shorter survival time.     

巨噬细胞浸润对胃癌进展和预后的影响*

目的:研究胃癌标本中巨噬细胞浸润与临床病理特征和预后的关系。方法:采用免疫组化SP法检测收集武汉大学中南医院肿瘤科的37例胃癌标本,通过高倍视野下巨噬细胞计数分析巨噬细胞浸润程度与临床病理因素的关系,重点分析其与预后的关系。结果:巨噬细胞主要分布于胃癌癌巢与间质交界处和间质血管丰富处,尤其在基底膜结构破坏处。高倍视野下对浸润巨噬细胞计数,37例胃癌患者平均巨噬细胞计数为19.7 ± 8.9 个;29例无远处转移患者平均巨噬细胞计数为18.9 ± 8.3 个。年龄、病理类型、复发与否、有无淋巴结转移对巨噬细胞浸润程度无影响（P 均>0.05）;远处转移组巨噬细胞计数（22.6 ± 11.0 个）高于无远处转移组（18.9 ± 8.3 个）,但差异无统计学意义（P=0.090）;侵及浆膜者浸润巨噬细胞计数（21.6 ± 8.0 个）明显高于未侵及浆膜者（12.7 ± 9.2 个）,P=0.011;晚期胃癌组织巨噬细胞浸润程度（22.6 ± 8.1 个）明显高于早期胃癌组织（12.8 ± 7.1 个）,P=0.001。37例胃癌患者总体生存期（中位数19.0 个月）与病理类型、淋巴结转移状况无明显相关,但与侵及浆膜、远处转移和TNM分期相关（P 值分别为0.024、0.021 和0.009）。 无瘤生存期（中位数13.0 个月）也与侵及浆膜（P=0.038）、TNM分期（P=0.006）密切相关。巨噬细胞高密度患者中位生存期（13.0 个月）短于低密度者（40.5 个月）,但无显著性差异（P=0.056）。 高密度巨噬细胞患者中位无瘤生存期（9.5 个月）明显低于低密度患者（37.0 个月）,P=0.041。结论:巨噬细胞浸润促进胃癌进展,浸润程度越高,胃癌进展越快,患者预后越差。      

Co-expression of thymidine phosphorylase and heme oxygenase-1 in macrophages in human malignant vertical growth melanomas.

Expression of thymidine phosphorylase (TP) is often associated with tumor angiogenesis and / or prognosis in patients. Further, infiltration of macrophages is closely correlated with the depth of tumor and angiogenesis in melanomas. In this study, we examined the expression of TP and an activated macrophage-specific enzyme, heme oxygenase-1 (HO-1), involved in malignancy in 22 cases with melanomas. TP was strongly expressed not only in CD68-positive macrophages in and around tumors, but also in S100 protein-positive melanoma cells, fibroblasts and keratinocytes. By contrast, HO-1 was specifically expressed in macrophages, but only slightly in melanoma cells and other cell types in the stroma of melanomas. We thus observed apparent co-expression of TP and HO-1 in macrophages infiltrating in the late stage of malignant melanomas. There appeared increasing numbers of TP-positive cells in Clark level IV and V melanoma compared with Clark level I (in situ) melanoma, and there was also a close correlation between numbers of TP-positive cells and HO-1-positive cells. Both TP- and HO-1-positive macrophages could be observed in the stroma in and around tumors in vertical growth melanomas.     

Co-expression of Thymidine Phosphorylase and Heme Oxygenase-1 in Macrophages in Human Malignant Vertical Growth Melanomas

Expression of thymidine phosphorylase (TP) is often associated with tumor angiogenesis and/or prognosis in patients. Further, infiltration of macrophages is closely correlated with the depth of tumor and angiogenesis in melanomas. In this study, we examined the expression of TP and an activated macrophage-specific enzyme, heme oxygenase-1 (HO-1), involved in malignancy in 22 cases with melanomas. TP was strongly expressed not only in CD68-positive macrophages in and around tumors, but also in S100 protein-positive melanoma cells, fibroblasts and keratinocytes. By contrast, HO-1 was specifically expressed in macrophages, but only slightly in melanoma cells and other cell types in the stroma of melanomas. We thus observed apparent co-expression of TP and HO-1 in macrophages infiltrating in the late stage of malignant melanomas. There appeared increasing numbers of TP-positive cells in Clark level IV and V melanoma compared with Clark level I ( in situ ) melanoma, and there was also a close correlation between numbers of TP-positive cells and HO-1-positive cells. Both TP- and HO-1-positive macrophages could be observed in the stroma in and around tumors in vertical growth melanomas.     

Localization of endostatin in rat and human gliomas

BACKGROUND: Endostatin is a potent inhibitor of endothelial cell proliferation, angiogenesis, and tumor growth. Its occurrence and localization has not yet been examined in human brain tumors. The authors report the production of a monoclonal antibody and detection of endostatin in rat and human gliomas by immunohistochemistry. METHODS: The authors analyzed localization and tissue distribution of endostatin in 41 paraffin embedded glioma samples (18 glioblastoma multiforme, 7 WHO Grade III astrocytomas, 13 fibrillary, and 3 protoplasmic WHO Grade II astrocytomas) of human origin and 21 rat C6 gliomas by immunohistochemistry. Double labeling experiments confirmed the origin of endostatin-labeled cells. RESULTS: Endostatin immunoreactivity was detected in tumor cells, endothelial cells, macrophages, and lymphocytes of both rat and human gliomas. The percentage of cells labeled with the endostatin antibody was significantly lower (P = 0.0126) in the tumor parenchyma of human glioblastomas than in WHO Grade II astrocytomas. CONCLUSIONS: Endostatin was present in various cell types in rat and human gliomas in vivo. Lower levels in glioblastomas than in WHO Grade II astrocytomas might have reflected the shift of a probable regulatory balance between promoters and inhibitors of angiogenesis towards facilitation of neovascularization.     

Angiogenesis and antiangiogenic therapy for malignant gliomas

Angiogenesis is crucial to the growth of malignant gliomas. Therefore, antiangiogenic therapy represents a new, promising therapeutic modality for malignant gliomas. This study was designed to define the malignant glioma cases most suitable for antiangiogenic therapy in humans and to demonstrate the efficacy of antiangiogenic therapy in animals. Protein expression of the most potent angiogenic factor, vascular endothelial growth factor (VEGF), and its specific natural inhibitor, soluble Flt-1, as well as vessel architecture, including vessel density, area, and diameter, was evaluated in human malignant glioma samples (24 glioblastomas, 13 anaplastic astrocytomas). Among these, VEGF >1000ng/ml, VEGF/soluble Fltl ratio >1, vessel density >30, and vessel area >7% were prognostic factors for malignant gliomas. Based on these results, we per formed three different antiangiogenic experiments targeted to inhibit VEGF expression in a human malignant glioma (U87) mouse model: anti-VEGF neutralized antibody intraperitoneal injection; interferon-beta intramusclar injection; and transfection of an endogenous nonspecific angiogenesis inhibitor, thrombospondin-1, into glioma cells caused inhibition of VEGF secretion and/or mRNA expression and resulted in glioma growth inhibition of 70%, 84%, and 50%, respectively, compared with control. We conclude that malignant gliomas with high degrees of VEGF expression and vessel areas are good candidates for antiangiogenic therapy, especially that designed to inhibit VEGF expression.     

HC gp-39 gene is upregulated in glioblastomas

Public databases of the Cancer Genome Anatomy Project were used to quantify the relative gene expression levels in glioblastoma multiforme (GBM) and normal brain by Serial Analysis of Gene Expression (SAGE). Analysis revealed HC gp-39 among the genes with the most pronounced changes of expression in tumor cells. Northern hybridization confirmed the results of computer analysis and showed that enhanced expression of the HC gp-39 gene was mainly in GBMs and occasionally in anaplastic astrocytomas. Neither SAGE nor Northern analysis revealed the presence of HC gp-39 mRNA in the glioblastoma cell line, thus the detection of increased quantities of this mRNA in GBMs may be associated with activated macrophages. Since the numbers of infiltrating macrophages and small vessel density are higher in glioblastomas than in anaplastic astrocytomas or astrocytomas, the HC gp-39 gene can be used as a molecular marker in the analysis of malignant progression of astrocytic gliomas.     

Correlation of Delta-like Ligand 4 (DLL4) with VEGF and HIF-1α Expression in Human Glioma

To investigate the potential role of the notch ligand delta-like ligand 4 (DLL4) in glioma angiogenesis, weexamined whether its expression correlates with that of vascular endothelial growth factor (VEGF) and hypoxiainducedfactor-1α (HIF-1α). Eighty-two specimens of human glioma and 7 of normal brain tissue were subjectedto immunohistochemical analysis for DLL4, VEGF and HIF-1α expression. Statistical analysis were performedto determine if protein expression correlated with clinicopathological parameters, including histological type,pathological grade, and microvessel density (MVD), determined using CD34-labelling. Expression of DLL4,VEGF and HIF-1α was very strong in gliomas, relative to normal tissues, linked with the malignant grade.Moreover, DLL4 staining positively correlated with VEGF and HIF-1α expression and with MVD. Thus ourresults indicate that DLL4 represents a potential biomarker and therapeutic target for glioma angiogenesis.     

Vasorin stimulates malignant progression and angiogenesis in glioma

Glioma, the most common human primary brain tumor, is characterized by invasive capabilities and angiogenesis. Vasorin (VASN), a transmembrane protein, is reported to be associated with vascular injury repair and is overexpressed in some human tumors. However, its role in tumor progression and angiogenesis in glioma is unknown. In this study, VASN was shown to be overexpressed in high‐grade gliomas, and the expression level correlated with tumor grade and microvessel density in glioma specimens. Glioma patients with high VASN expression had a shorter overall survival time. Knockdown of VASN in glioma cells by shRNA significantly inhibited the malignancy of glioma, including cell proliferation, colony formation, invasion, and sphere formation. Ectopic expression of VASN increased glioma progression in vitro. The expression of VASN correlated with the mesenchymal type of glioblastoma multiforme (GBM) subtyped by gene set enrichment analysis (GSEA). Our results showed that the concentration of VASN was increased in the conditioned medium (CM) from glioma cells with VASN overexpression, and the CM from glioma cells with knockdown or overexpressed VASN inhibited or promoted HUVEC migration and tubulogenesis in vitro, respectively. Glioma growth and angiogenesis were stimulated upon ectopic expression of VASN in vivo. The STAT3 and NOTCH pathways were found to be activated and inhibited by VASN overexpression. Our findings suggest that VASN stimulates tumor progression and angiogenesis in glioma, and, as such, represents a novel therapeutic target for glioma.     

Induced interleukin-8 expression in gliomas by tumor-associated macrophages

The tumor microenvironment affects tumor initiation, progression, and metastasis. However, it is still not clear how stromal cells interact with the tumor cells. By using a cytokine array immunoblot assay, we showed that interleukin (IL)-8, IL-6, and RANTES (regulated upon activation normal T-cell expressed and secreted) proteins were up-regulated in GBM8401 glioma cells after coculture with human THP-1-derived macrophages. IL-8 is a chemokine with leukocyte chemotactic, tumorigenic, and proangiogenic properties. To evaluate the correlation of IL-8 expression with tumor-associated macrophages and angiogenesis, 43 glioma specimens were studied. The results showed that the IL-8 mRNA expression and microvessel count in glioma surgical specimens correlated positively with the density of tumor-associated macrophages. We further showed that IL-8 mRNA expression in GBM8401 cells increased dramatically, by 2⁸–2¹⁰-fold, after being cocultured with macrophages. This increase could also be induced by macrophage-conditioned medium, tumor necrosis factor-α, IL-1α, and IL-1β, and could be suppressed by anti-inflammatory agents including pyrrolidine dithiocarbamate, pentoxifylline, or dexamethasone. These findings imply that macrophage infiltration may be the common feature shared by cancer and inflammation, and macrophages could play a role in promoting glioma growth and angiogenesis by inducing IL-8 expression in glioma cells via inflammatory stimuli or the nuclear factor kappa B pathway.     

4F2hc表达与人脑胶质瘤病理级别增殖和血管形成的关系

  目的  探讨细胞表面抗原4F2重链(4F2 heavy chain, 4F2hc)在人脑胶质瘤组织中的表达水平及其与胶质瘤病理学特征、细胞增殖以及血管形成的关系。  方法  采用免疫组化方法检测4F2hc、Ki-67和CD34在62例人脑胶质瘤组织中的表达, 计数Ki-67标记指数(Ki-67 LI)和微血管密度(MVD)。  结果  4F2hc在胶质瘤中高表达, 其免疫阳性染色既定位于瘤细胞也定位于血管内皮; 4F2hc表达随胶质瘤病理级别升高而明显增强(P=0.001), 在高度恶性胶质瘤中4F2hc表达明显强于低度恶性胶质瘤(P=0.002);4F2hc表达与胶质瘤Ki-67标记指数存在明显正相关(P=0.003), 但与微血管密度无明显相关性(P=0.214)。  结论  4F2hc与胶质瘤的发生和发展关系密切, 可能在胶质瘤的恶性增殖过程中具有重要作用。      

Biological role of thymidine phosphorylase in human astrocytic tumors

Thymidine phosphorylase (TP) has strong angiogenic activity and is overexpressed in a wide variety of malignant tumors. To elucidate the role of TP in human astrocytic tumors, we immunohistochemically investigated the expression of TP in 62 astrocytic tumors (12 astrocytomas, 12 anaplastic astrocytomas and 38 glioblastomas). Fifty-five astrocytic tumors (88.7%) were immunopositive for TP. The level of TP-expression was significantly correlated with the malignancy grade of astrocytic tumors; most of malignant gliomas highly expressed TP, while a small number of cells were positive in low grade astrocytomas (p < 0.001). Using double-immunostaining, we clarified that TP-expression was predominantly detectable in macrophages. There was no significant correlation between MIB-1 labeling index and TP-expression. However, TP-expression and the microvessel density were well correlated. These suggest that TP, mainly produced by the infiltrated macrophages, may play an important role in the progression of astrocytic tumors via neovascularization. Inhibitor of TP may represent a therapeutic modality for treating malignant gliomas.     

Monocyte chemoattractant protein-1 expression correlates with macrophage infiltration and tumor vascularity in human gastric carcinomas

The purpose of this study was to investigate the role of interactions between tumor cells and macrophages during angiogenesis in human gastric carcinomas. Macrophage infiltration into tumors and monocyte chemoattractant protein-1 (MCP-1) expression was assessed in 72 archival specimens of gastric carcinoma for comparison with tumor vascularity. The mRNA expression of MCP-1 was examined by RT-PCR in 6 gastric carcinoma cell lines and in fresh biopsy specimens from 18 patients. Immunolocalization of representative angiogenic factors, vascular endothelial growth factor (VEGF), and platelet-derived endothelial cell growth factor (PD-ECGF) was also done. MCP-1 expression in tumor cells increased with the depth of tumor invasion (Tis 9.5%, T1 19.4%, T2-4 60.0%), as did microvessel density and macrophage infiltration. Macrophage counts correlated with vessel counts, and both were significantly higher in MCP-1-positive than in negative tumors. Of the 6 gastric carcinoma cell lines, 2 constitutively expressed MCP-1 mRNA. In 6 (33.3%) of 18 biopsy samples, MCP-1 mRNA was expressed at higher levels in tumor tissues than in normal mucosa. VEGF protein was expressed by gastric carcinoma cells, whereas PD-ECGF protein was expressed mainly by stromal mononuclear cells. MCP-1 expression correlated significantly with VEGF but not PD-ECGF expression in gastric carcinomas. These results suggest that MCP-1 produced by human gastric carcinoma cells plays a role in angiogenesis via macrophage recruitment and activation.     

Monocyte chemoattractant protein-1 transfection induces angiogenesis and tumorigenesis of gastric carcinoma in nude mice via macrophage recruitment.

PURPOSE: Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that has various roles in tumor development and progression. We previously reported that expression of MCP-1 is associated with macrophage infiltration and tumor vessel density in human gastric carcinomas. The present study was undertaken to obtain direct evidence that MCP-1 participates in recruitment of macrophages and induction of angiogenesis. EXPERIMENTAL DESIGN: We did transfection experiments to analyze the role of MCP-1 in tumorigenicity and angiogenesis in gastric carcinoma in nude mice. The human MCP-1 gene cloned into the BCMGS-Neo expression vector was transfected into the human gastric carcinoma TMK-1 cell line. We examined tumor volumes with the ectopic s.c. xenograft model and tumorigenicity with the orthotopic gastric xenograft model. We determined intratumor microvessel counts and tumor-infiltrating macrophage counts by immunohistochemical staining. RESULTS: There was no difference in in vitro proliferation between MCP-1-transfected TMK-1 cells and mock-transfected (control) cells; however, MCP-1 transfectants induced tumor growth in ectopic xenografts and increased tumorigenicity and induced lymph node metastases and ascites in orthotopic xenografts. In both ectopic and orthotopic xenograft models, strong infiltration of macrophages was observed within and around the tumors after implantation of MCP-1 transfectants whereas fewer macrophages were seen after inoculation of control cells. The microvessel density was significantly higher in tumors produced by MCP-1 transfectants than in control tumors. CONCLUSIONS: MCP-1 produced by gastric carcinoma cells may regulate angiogenesis via macrophage recruitment. MCP-1 may be a potential target for antiangiogenic therapy for gastric carcinoma.     

EphA2及其配体EphrinA1在恶性脑胶质瘤中的表达及与血管生成的关系

  目的  检测酪氨酸激酶受体EphA2及其配体EphrinA1在恶性脑胶质瘤中的表达,并探讨其与胶质瘤血管生成的关系。  方法  采用免疫组织化学S-P法检测62例胶质瘤组织及8例正常脑组织中EphA2、EphrinA1的表达情况,并采用CD105抗体标记微血管内皮细胞,计算微血管密度（microvesseldensity,MVD）。探讨EphA2、EphrinA1的表达水平与胶质瘤的微血管生成之间可能存在的关系。  结果  EphA2、MVD在胶质瘤中阳性表达明显高于正常脑组织,二者差异显著（P<0.01）。而且随着肿瘤恶性程度增加,EphA2及MVD蛋白染色强度和阳性细胞数均明显升高,高级别脑胶质瘤（Ⅲ~Ⅳ）中EphA2及MVD强阳性表达明显高于低级别胶质瘤组,差异有显著统计学意义（P<0.01）。EphrinA1则具有相反的趋势,在大多数恶性脑胶质瘤中呈低水平表达,在低级别胶质瘤和正常组织中呈较高水平表达,且胶质瘤级别越低EphrinA1表达越高。EphA2表达与MVD呈显著正相关（r=0.713,P<0.01）,EphrinA1表达与MVD呈显著负相关（r=-0.772,P<0.01）,EphA2的表达与EphrinA1呈显著负相关（r=-0.912,P<0.01）。  结论  EphA2在恶性脑胶质瘤中特异性高表达、EphrinA1特异性低表达与胶质瘤的侵袭性和恶性程度密切相关,且EphA2过表达和EphrinA1的缺陷表达可能协同促进胶质瘤组织新生血管的生成,在胶质瘤的发病及恶性进展中发挥重要作用。