trans-3,4,5'-Trihydroxystibene inhibits hypoxia-inducible factor 1alpha and vascular endothelial growth factor expression in human ovarian cancer cells.

trans-3,4,5'-Trihydroxystibene (resveratrol) is a natural product commonly found in the human diet and has been shown recently to have anticancer effects on various human cancer cells. However, the molecular basis for its anticancer action remains to be elucidated. In this study, we investigated the effect of resveratrol on hypoxia-inducible factor 1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) expression in human ovarian cancer cells A2780/CP70 and OVCAR-3. We found that although resveratrol did not affect HIF-1alpha mRNA levels, it did dramatically inhibit both basal-level and growth factor-induced HIF-1alpha protein expression in the cells. Resveratrol also greatly inhibited VEGF expression. Mechanistically, we demonstrated that resveratrol inhibited HIF-1alpha and VEGF expression through multiple mechanisms. First, resveratrol inhibited AKT and mitogen-activated protein kinase activation, which played a partial role in the down-regulation of HIF-1alpha expression. Second, resveratrol inhibited insulin-like growth factor 1-induced HIF-1alpha expression through the inhibition of protein translational regulators, including M(r) 70,000 ribosomal protein S6 kinase 1, S6 ribosomal protein, eukaryotic initiation factor 4E-binding protein 1, and eukaryotic initiation factor 4E. Finally, we showed that resveratrol substantially induced HIF-1alpha protein degradation through the proteasome pathway. Our data suggested that resveratrol may inhibit human ovarian cancer progression and angiogenesis by inhibiting HIF-1alpha and VEGF expression and thus provide a novel potential mechanism for the anticancer action of resveratrol.     

Flaxseed inhibits metastasis and decreases extracellular vascular endothelial growth factor in human breast cancer xenografts

Angiogenesis is important in tumor growth, progression and metastatic dissemination. Vascular endothelial growth factor (VEGF) is one key factor in promotion of breast cancer angiogenesis. VEGFs are bioactive in the extracellular space where they become available to the endothelial cells. Phytoestrogens such as lignans have been shown to alter breast cancer incidence and be cancer-protective in rats. We show that supplementation of 10% flaxseed, the richest source of mammalian lignans, to nude mice with established human breast tumors reduced tumor growth and metastasis. Moreover, flaxseed decreased extracellular levels of VEGF, which may be one mechanistic explanation to the decreased tumor growth and metastasis.     

HIF-1α、VEGF在乳腺浸润性导管癌中的表达及临床意义

目的研究缺氧诱导因子-1α（hypoxia inducible factor-1 alpha，HIF-1α）和血管内皮生长因子（vascular endothelial growth factor，VEGF）的基因严物在乳腺浸润性导管癌（invasive ductal carcinoma，IDC）组织中的表达及其意义。方法应用免疫组化Envision^TM二步法检测86例乳腺IDC和10例乳腺腺病中HIF-1α和VEGF蛋白的表达。结果HIF-1α在86例乳腺IDC组织和乳腺腺病中曲阳性表达率分别为55．8％（48／86）和0％（0／10），差异有显著性（χ^2=11．16，P〈0．01）。乳腺IDC组织中，HIF-1α表达与乳腺IDC的肿块大小（r=0．257，P〈0．05）、TNM分期（r=0．342，P〈0．01）、组织学分级（r=0．393，P〈0．01）、淋巴结转移（r=0．391，P〈0．01）和肿瘤坏死（r=0．595，P〈0．01）呈正相关。VEGF蛋白在86例乳腺IDC组织和乳腺腺病中的阳性表达率分别为61．6％／（53／86）和0％（0／10），差异有显著性（χ^2=13．76，P〈0．01）。乳腺IDC组织中，VEGF表达与乳腺IDC的肿块大小（r=0．274，P〈0．01）、TNM分期（r=0．284，P〈0．01）、组织学分级（r=0．363，P〈0．01）、淋巴结转移（r=0．319，P〈0．01）和肿瘤坏死（r=0．592，P〈0．01）呈正相关。HIF-1α和VEGF蛋白的表达与患者年龄和术后5年生存率均无关。Spearman相关分析发现HIF-1α与VEGF表达程度呈正相关（r=0．636，P〈0．01）。结论乳腺IDC组织中HIF-1α基因表达显著增高，并可能诱导VEGF的过表达并与乳腺癌的侵袭性生物学行为密切相关。     

Brain-derived neurotrophic factor activation of TrkB induces vascular endothelial growth factor expression via hypoxia-inducible factor-1alpha in neuroblastoma cells

The extent of angiogenesis and/or vascular endothelial growth factor (VEGF) expression in neuroblastoma tumors correlates with metastases, N-myc amplification, and poor clinical outcome. Recently, we have shown that insulin-like growth factor-I and serum-derived growth factors stimulate VEGF expression in neuroblastoma cells via induction of hypoxia-inducible factor-1alpha (HIF-1alpha). Because another marker of poor prognosis in neuroblastoma tumors is high expression of brain-derived neurotrophic factor (BDNF) and its tyrosine kinase receptor, TrkB, we sought to evaluate the involvement of BDNF and TrkB in the regulation of VEGF expression. VEGF mRNA levels in neuroblastoma cells cultured in serum-free media increased after 8 to 16 hours in BDNF. BDNF induced increases in VEGF and HIF-1alpha protein, whereas HIF-1beta levels were unaffected. BDNF induced a 2- to 4-fold increase in VEGF promoter activity, which could be abrogated if the hypoxia response element in the VEGF promoter was mutated. Transfection of HIF-1alpha small interfering RNA blocked BDNF-stimulated increases in VEGF promoter activity and VEGF protein expression. The BDNF-stimulated increases in HIF-1alpha and VEGF expression required TrkB tyrosine kinase activity and were completely blocked by inhibitors of phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR) pathways. These data indicate that BDNF plays a role in regulating VEGF levels in neuroblastoma cells and that targeted therapies to BDNF/TrkB, PI3K, mTOR signal transduction pathways, and/or HIF-1alpha have the potential to inhibit VEGF expression and limit neuroblastoma tumor growth.     

RUNX3 inhibits the expression of vascular endothelial growth factor and reduces the angiogenesis, growth, and metastasis of human gastric cancer.

PURPOSE: Recent studies indicated that RUNX3 exhibits potent antitumor activity. However, the underlying molecular mechanisms of this activity remain unclear. In the present study, we used a gastric cancer model to determine the effect of RUNX3 expression on tumor angiogenesis. EXPERIMENTAL DESIGN: The effects of increased RUNX3 expression on vascular endothelial growth factor (VEGF) expression in and angiogenic potential of human gastric cancer cells were determined in vitro and in animal models. RUNX3 and VEGF expression was determined in 120 human gastric cancer specimens and their relationship was analyzed. RESULTS: RUNX3 gene transfer suppressed VEGF expression in human gastric cancer cells. Down-regulation of VEGF expression correlated with a significantly impaired angiogenic potential of human gastric cancer cells. Furthermore, RUNX3 restoration inhibited tumor growth and metastasis in animal models, which was consistent with inhibition of angiogenesis as determined by evaluating VEGF expression and tumor microvessel formation. In gastric cancer specimens, loss or decrease in RUNX3 expression inversely associated with increased VEGF expression and elevated microvessel formation. CONCLUSIONS: Our clinical and experimental data provide a novel molecular mechanism for the antitumor activity of RUNX3 and may help design effective therapy targeting RUNX3 pathway to control gastric cancer growth and metastasis.     

Endothelin-1-, endothelin-A-, and endothelin-B-receptor expression is correlated with vascular endothelial growth factor expression and angiogenesis in breast cancer.

PURPOSE: Endothelin-1 (ET-1) and its receptors (ET(A)R and ET(B)R), referred to as the endothelin (ET) axis, are overexpressed in breast carcinomas, and influence tumorigenesis and tumor progression by various mechanisms, including angiogenesis. The objective of the study was to clarify if expression of the ET axis participates in angiogenesis of breast carcinoma EXPERIMENTAL DESIGN: We analyzed expression of ET-1, ET(A)R, ET(B)R, and vascular endothelial growth factor (VEGF) immunohistochemically in 600 tissue array specimens from 200 paraffin-embedded breast carcinomas performing tissue microarray technology. Microvessel density (MVD) was determined by counting microvessels (identified by factor VIII) in each core specimen. RESULTS: Moderate or strong immunostaining was observed for ET-1 in 25.4%, for ET(A)R in 43.7%, and for ET(B)R in 22.2% of breast carcinomas. Of all cases, 44.7% showed significant expression of VEGF. MVD varied between different tumor specimens (range, 0-80; median, 17). We observed a statistically significant correlation between MVD and ET expression status with higher MVD in ET-positive tumors. Moreover, expression of VEGF was found more frequently in tumors with overexpression of the ET axis (each P < 0.001). Staining of VEGF was correlated positively with MVD CONCLUSIONS: These results indicate that increased ET-1, ET(A)R, and ET(B)R expression is associated with increased VEGF expression and higher vascularity of breast carcinomas and, thus, could be involved in the regulation of angiogenesis in breast cancer. Our findings provide evidence that the expression pattern of the ET-axis and in particular of ET(A)R may have clinical relevance in future antiangiogenic targeted therapies for breast cancer.     

Expression of hypoxia-inducible factor (HIF)-1alpha is associated with vascular endothelial growth factor expression and tumour angiogenesis in human oesophageal squamous cell carcinoma

The purpose of this study was to examine the relationship between hypoxia inducible factor (HIF)-1alpha expression, vascular endothelial growth factor (VEGF) expression, and tumour vascularity in squamous cell carcinoma of the oesophagus. Expression of HIF-1alpha and VEGF was examined in two oesophageal squamous cell carcinoma cell lines (TE2, TE3) and 82 archival surgical specimens of human oesophageal squamous cell carcinoma tissue. In both cell lines, the levels of HIF-1alpha protein and VEGF mRNA were increased under hypoxic conditions. Thirty-two of the 82 (39%) tumour specimens showed high levels of HIF-1alpha immunoreactivity in the nuclei and/or cytoplasm of cancer cells. HIF-1alpha expression correlated significantly with venous invasion, VEGF expression, and microvessel density. Among the 47 patients who did not receive pre-operative chemotherapy, the outcome of those with high HIF-1alpha-expressing tumours was significantly poorer than that of those with low HIF-1alpha-expressing tumours. These results suggest that HIF-1alpha and VEGF expression are important determinants of survival in squamous cell carcinoma of the oesophagus.     

Restoration of wild-type p16 down-regulates vascular endothelial growth factor expression and inhibits angiogenesis in human gliomas.

Recent studies have indicated that the loss of p16 is a frequent event in the progression of malignant gliomas. The loss of p16 promotes the acquisition of malignant characteristics in gliomas, which are among the most angiogenic of all human tumors. High-grade gliomas are distinguished from low-grade gliomas by intense angiogenesis in addition to their frequent loss of p16. New therapeutic strategies aimed at inhibiting tumor angiogenesis on the basis of molecular mechanisms are theoretically attractive. Here we evaluate the effect of p16 gene replacement on the angiogenesis of gliomas. Infection with a recombinant replication-defective adenovirus vector containing the cDNA of wild-type p16 significantly reduced the expression of vascular endothelial growth factor, which is thought to be a pivotal mediator of tumor angiogenesis, in p16-deleted glioma cells. Restoring wild-type p16 expression into p16-deleted glioma cells markedly inhibited angiogenesis induced by tumor cells in vivo. Furthermore, wild-type p16 inhibited neovascularization more potently than did wild-type p53 transfer. These findings indicate that the p16 gene plays an important role in the regulation of glioma angiogenesis, suggesting a novel function of the p16 gene.     

S-1 inhibits tumorigenicity and angiogenesis of human oral squamous cell carcinoma cells by suppressing expression of phosphorylated Akt, vascular endothelial growth factor and fibroblast growth factor-2

It has been reported that S-1 can exert antitumor effects on various human cancers including oral squamous cell carcinoma (OSCC). However, little is known about the detailed mechanisms of the antitumor activity of S-1. In the present study, we determined whether S-1 could suppress the angiogenesis and growth of human OSCC cells in vitro and in vivo. The S-1 component (5-FU plus CDHP) significantly suppressed the growth and migration of OSCC cells and BAEC, which inhibited tubule formation in HUVECs in vitro. Also, S-1 inhibited the nuclear factor-kappaB (NF-kappaB) activity in human OSCC cells in vitro. Moreover, S-1 inhibited the expression of survival signal, phosphorylated Akt (p-Akt), and of two major proangiogenic molecules, vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2), in cells implanted into the subcutaneous tissue of nude mice. The decreased expression of p-Akt, VEGF and FGF-2 correlated with decreased tumorigenicity and decreased vascularization of lesions in vivo. These findings suggest that S-1 can suppress the angiogenesis and growth of OSCC cells by inhibiting the expression of p-Akt, VEGF and FGF-2 involved in the blockade of Akt/NF-kappaB pathway.