Inhibition of infiltration and angiogenesis by thrombospondin-1 in papillary thyroid carcinoma.

PURPOSE: Angiogenesis is essential for tumor growth and is controlled by the balance between angiogenic and antiangiogenic factors. We studied the expression of angiogenic factors and antiangiogenic factors in papillary thyroid carcinoma. EXPERIMENTAL DESIGN: We investigated immunohistochemically the expression patterns and levels of antiangiogenic factor and its receptor, thrombospondin-1 (TSP-1) and CD36, and four angiogenic factors, vascular endothelial growth factor (VEGF), VEGF-C, angiopoietin-2 (Ang-2), and Tie-2, in the primary tumors of 75 papillary thyroid carcinoma patients. We also examined the microvessel count (MVC), using CD31 staining. RESULTS: VEGF expression strongly correlated with other angiogenic factors. The cytoplasm of cancer cells stained positive for all factors. Tie-2 and TSP-1 receptor also appeared in endothelia of microvessels. TSP-1 inversely correlated with the degree of invasion of the primary tumor to other adjacent organs and with MVC. A higher MVC correlated with poorer survival. To clarify the balance between angiogenic and antiangiogenic factors in the same tumor, we calculated the ratio of each angiogenic factor against TSP-1 as the antiangiogenic factor. The ratios VEGF/TSP-1, VEGF-C/TSP-1, and Ang-2/TSP-1 significantly correlated with a higher MVC. Furthermore, the ratios VEGF/TSP-1 and Ang-2/TSP-1 significantly correlated with the degree of infiltration. CONCLUSIONS: To the best of our knowledge, this is the first report demonstrating that the balance between angiogenic and antiangiogenic factors correlates with distinct invasion to other organs and neovascularization of papillary thyroid carcinoma.     

Vascular endothelial growth factor-B and vascular endothelial growth factor-C expression in renal cell carcinomas: regulation by the von Hippel-Lindau gene and hypoxia

Angiogenesis is essential for tumor growth and metastasis. It is regulated by numerous angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF). Recently VEGF-B and VEGF-C, two new VEGF family members, have been identified that bind to the tyrosine kinase receptors flt-1 (VEGFR1), KDR (VEGFR2), and flt-4 (VEGFR3). Although the importance of VEGF-A has been shown in renal carcinomas, the contribution of these new ligands in kidney tumors is not clear. We have, therefore, measured the mRNA level of VEGF-B and VEGF-C together with their receptors by RNase protection assay (RPA) in 26 normal kidney samples and 45 renal cell cancers. We observed a significant up-regulation of VEGF-B (P = 0.002) but not VEGF-C (P = 0.3) in neoplastic kidney compared with normal tissues. In addition, although VEGF receptors were higher in tumors than normal kidney, there was a significant up-regulation of only flt-1 (P = 0.003) but not KDR (P = 0.12) or flt-4 (P = 0.09). There was also a significant correlation between VEGF-C and both of its receptors flt-4 (P = 0.006) and KDR (P = 0.03) but no association between VEGF-B and its receptor flt-1 (P = 0.23). A significant increase was observed in flt-1 (P < 0.001), KDR (P = 0.02), and flt-4 (P = 0.01) but not VEGF-B (P = 0.82) or VEGF-C (P = 0.52) expression in clear cell compared with chromophil (papillary) carcinomas. No significant association was demonstrated between VEGF-B, VEGF-C, flt-1, KDR, and flt-4 with patient sex, patient age, or tumor size (P > 0.05). The effect of von Hippel-Lindau (VHL) gene and hypoxia on VEGF-B and VEGF-C expression in the renal carcinoma cell line 786-0 transfected with wild-type and mutant VHL was determined by growing cells under 21% O2- and 0.1% O2. In wild-type VHL cells, whereas VEGF-A was significantly up-regulated under hypoxic compared with normoxic conditions (P < 0.001), expression of VEGF-C was reduced (P < 0.002). Nevertheless, the repression of VEGF-C was lost in mutant VHL cell lines under hypoxia. In contrast VEGF-B was not regulated by VHL despite clear up-regulation in vivo. These findings strongly support an enhanced role for this pathway in clear cell carcinomas by regulating angiogenesis and/or lymphangiogenesis. The study shows that clear cell tumors are able to up-regulate angiogenic growth factor receptors more efficiently than chromophil (papillary), that clear cell tumors can use pathways independent of VHL to regulate angiogenesis, and that this combined regulation may account for their more aggressive phenotype, which suggests that targeting VEGFR1 (flt-l) may be particularly effective in these tumor types.     

Modulation of the angiogenesis response through Ha-ras control,placenta growth factor,and angiopoietin expression in mouse skin carcinogenesis

Tumor angiogenesis is governed by a complex balance of positive and negative angiogenic factors. Development of chemically-induced mouse skin tumors appears to be highly dependent on an early burst of neovascularization. We have previously shown that Ha-ras-driven vascular endothelial growth factor (VEGF) expression plays a pivotal role in this process. However, the status of other critical positive and negative angiogenic factors throughout skin tumorigenesis has not been studied to the same extent. In the present study, we show that another VEGF family member, placenta growth factor (PlGF), was highly upregulated at all tumor stages in a ras-dependent manner. The study of angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2), ligands of receptor tyrosine kinase 2 (Tie-2), showed that while stroma-derived Ang-2 was increased, epidermal Ang-1 expression was completely abolished at early papilloma formation. Studies using epidermal tumor cell lines suggest that the disappearance of Ang-1 also depends on ras activation, extending the plethora of events controlled by this oncogene in mouse skin carcinogenesis. Our results indicated that tumor development occurred in a strong angiogenesis-prone scenario in which PlGF and Ang-2 acted cooperatively with VEGF, whereas the negative or stabilizing effect of Ang-1 was abrogated. A time-course sequence of expression of angiogenic factors expressed throughout tumor growth, as well as the identification of key signaling molecules triggering the angiogenic response, may contribute to the development and testing of antiangiogenic therapeutic strategies with this in vivo tumor model.     

Expression analysis of vascular endothelial growth factors and their relationships to lymph node metastasis in human colorectal cancer

This study was undertaken to determine whether expressions of the vascular endothelial growth factor (VEGF) family (VEGF-A, VEGF-B, VEGF-C, and VEGF-D) are correlated with clinicopathological parameters, with particular reference to lymph node metastasis in colorectal cancer. Total RNA was isolated from 82 surgical specimens of colorectal cancer and matched to normal mucosa with (n = 41) or without (n = 41) lymph node metastasis. The mRNA expression of each VEGF family member was quantified by real-time quantitative (RTQ) RT-PCR assay. VEGF-B and VEGF-C mRNA were significantly higher both in the tumors with lymph node metastasis (p = 0.027 and p = 0.024, respectively) and in tumors with lymphatic invasion (p = 0.042 and p = 0.005, respectively). In contrast, VEGF-D mRNA was down-regulated in tumors with lymphatic involvement (p = 0.047). Among the other clinicopathological factors, we noted that VEGF-A mRNA was higher in tumors with liver metastasis than in those without (p = 0.018) and was higher in tumors with venous invasion than in those without (p = 0.007). The results of this study demonstrate that high levels of VEGF-B, C and low levels of VEGF-D mRNA expression are associated with lymph node metastasis and lymphatic involvement. These results suggest that a balance among VEGF-B, VEGF-C, and VEGF-D might contribute to the lymphangiogenic process and metastasis in colorectal cancer.     

Nuclear factor kappaB dependency of platelet-activating factor-induced angiogenesis

This study investigated the mechanisms of platelet-activating factor (PAF)-induced angiogenesis in a mouse model of Matrigel implantation. PAF induced a dose- and time-dependent angiogenic response. Inhibitors of nuclear factor (NF) kappaB expression or action, including antisense oligonucleotides to the p65 subunit of NFkappaB (p65 antisense) and antioxidants such as alpha-tocopherol and N-acetyl-L-cysteine, significantly reduced PAF-induced angiogenesis. In human umbilical vein endothelial cells, PAF-induced mRNA expression and protein synthesis of various NFkappaB-dependent angiogenic factors, such as tumor necrosis factor-alpha, interleukin-1alpha, basic fibroblast growth factor, and vascular endothelial growth factor (VEGF). The PAF-induced expression of the above mentioned factors was inhibited by p65 antisense or antioxidants. A significant inhibition of the angiogenic effect of PAF was achieved by anti-VEGF antibodies or soluble VEGF receptors such as KDR and flt-1 but not by antibodies against tumor necrosis factor-alpha, interleukin-1alpha, or basic fibroblast growth factor. These data indicate that PAF enhances angiogenesis through inducing NFkappaB activation, which in turn promotes the production of angiogenic factors such as VEGF.     

Serum Vascular Endothelial Growth Factors A, C and D in Human Breast Tumors

Available evidence suggests that vascular endothelial growth factor (VEGF) a potent regulator of vasculogenesis and tumor angiogenesis may be a predictor of recurrence in breast cancer patients. We sought to determine whether VEGF serum levels (VEGF-A, VEGF-C and VEGF-D) in 377 patients with malignant and benign breast tumors differ and whether there is association between vascular growth factors, clinicopathologic features and prognosis. There was no significant difference in investigated circulating angiogenic markers between patients with malignant and non malignant lesions. We found strong correlation between VEGF-A and VEGF-D and between VEGF- C and VEGF-D. Besides serum VEGF-D levels and estrogen receptor (ER) expressions no other correlations between VEGF and clinicopathologic variables were observed. However, elevated VEGF-A and VEGF-C concentrations were associated with increased number of erythrocytes, leukocytes and platelets. In Cox model values of angiogenic serum markers and recognized prognostic markers in breast cancer, VEGF-C turned out as independent prognostic factor. Our study is the first analysis showing correlation between serum concentrations of three angiogenic factors: VEGF-A, VEGF-C, VEGF-D. Associations between angiogenic cytokines and number of blood cells may be due to release of VEGF from platelets and leucocytes. Prognostic role of VEGF is still uncertain, though VEGF-C has a potential to serve as a prognostic marker.     

VEGF在恶性肿瘤中的研究进展

肿瘤的生长依赖肿瘤新生血管的形成，血管内皮生长因子（VEGF）及其家族是重要的血管生成正性调节因子，VEGF家族包括VEGF-A﹑VEGF-B ﹑VEGF-C﹑ VEGF-D ﹑VEGF-E和胎盘生长因子，本文旨在对VEGF家族的结构、功能、调控等方面的研究作一综述。     

Clinical implications of circulating angiogenic factors in cancer patients.

PURPOSE: Angiogenesis, a process fundamental to tumor growth, is regulated by angiogenic factors. This article reviews prognostic and other clinical implications of circulating angiogenic factors in cancer patients. METHODS: A MEDLINE search of literature was performed using the names of various angiogenic factors as the key words. Studies pertaining to circulating angiogenic factors in cancer patients were reviewed. Pertinent literature regarding tumor expression of common angiogenic factors and their prognostic relevance in human cancers were also examined. RESULTS: A substantial number of studies have demonstrated a strong association between elevated tumor expression of vascular endothelial growth factor (VEGF) and advanced disease or poor prognosis in various cancers. This supports the pivotal role of VEGF in regulating tumor angiogenesis. More recently, there is mounting evidence that the level of circulating VEGF in patients with different types of cancer may be predictive of tumor status and prognosis. Preliminary data also suggest that circulating VEGF may be useful in predicting and monitoring tumor response to anticancer therapies and in follow-up surveillance for tumor relapse. There are reports supporting the prognostic value of other circulating angiogenic factors such as basic fibroblast growth factor, platelet-derived endothelial cell growth factor, transforming growth factor-beta, and angiogenin, but their clinical significance is less conclusive because of limited data. CONCLUSION: Circulating VEGF seems to be a reliable surrogate marker of angiogenic activity and tumor progression in cancer patients. Evaluation of circulating angiogenic factors is a promising novel approach of prognostication in cancer patients that has the advantages of being convenient and noninvasive, and it may provide new prognostic information that is not afforded by conventional clinicopathologic prognostic indicators.     

ErbB2 overexpression correlates with increased expression of vascular endothelial growth factors A,C, and D in human breast carcinoma

BACKGROUND: The angiogenic factor vascular endothelial growth factor (VEGF)-A plays an important role in breast cancer progression. However, the involvement of VEGF-C and VEGF-D, two newer members of the VEGF family, in breast carcinoma and their relationship with clinicopathologic parameters have not been clearly demonstrated. METHODS: In this study, the expression levels of VEGF-A, VEGF-C, and VEGF-D protein in 107 breast carcinoma cases and 22 nonmalignant breast tissue samples were examined by immunohistochemistry and quantitated by image analysis. RESULTS: Higher expression of VEGF-C and VEGF-D was found in breast carcinomas than in nonmalignant breast tissue samples. Moreover, expression of VEGF-A, VEGF-C, and VEGF-D was significantly and positively correlated with ErbB2 expression. High levels of VEGF-A expression were associated with shorter disease-free survival (DFS). Patients with tumors expressing high levels of VEGF-C or VEGF-D showed a notable trend for worse DFS, however, it was not statistically significant. The combination of VEGF-A and VEGF-C status predicted survival better than either marker alone. CONCLUSIONS: Our study suggests that expression of the angiogenic and lymphangiogenic factors (i.e., VEGFs) might be regulated at least in part by ErbB2. In addition, the combination of VEGF-A and VEGF-C status may better predict prognosis of patients with breast carcinoma than VEGF-A alone.