Angiogenesis inhibitors. A promising role in cancer therapy

Reduction of metastatic and angiogenic potency of malignant cancer by Eupatorium fortunei via suppression of MMP-9 activity and VEGF production

Eupatorium fortunei has long been used to treat nausea and poor appetite, and has been prescribed as a diuretic and detoxifying drug in Chinese medicine. Recent studies have demonstrated that E. fortunei possesses anti-bacterial, anti-oxidant, and anti-diabetic activities, as well as cytotoxicity to human leukemia cells. However, at non-toxic concentrations, the effects of an aqueous extract of E. fortunei (WEF) on the metastatic and angiogenic potential of malignant tumor cells have not been reported. In this study, we found that WEF suppressed the metastatic properties, including anchorage-independent colony formation, migration, and invasion, by downregulating the proteolytic activity of MMP-9. NF-κB activation and the phosphorylation of p38 and JNK were reduced significantly by WEF. Additionally, WEF inhibited tumor-induced angiogenesis markedly, affecting HUVEC migration, tube formation by HUVECs, and microvessel sprouting from rat aortic rings via a reduction in VEGF in tumors. In a pulmonary metastasis model, daily administration of WEF at 50 mg/kg markedly decreased metastatic colonies of intravenously injected B16F10 cells on the lung surface in C57BL/6J mice. Further, none of the WEF-administered mice exhibited systemic toxicity. Taken together, our results indicate that WEF is a potential therapeutic herbal product that may be useful for controlling malignant metastatic cancer.

The role of CXC chemokines in pulmonary fibrosis

The CXC chemokine family is a pleiotropic family of cytokines that are involved in promoting the trafficking of various leukocytes, in regulating angiogenesis and vascular remodeling, and in promoting the mobilization and trafficking of mesenchymal progenitor cells such as fibrocytes. These functions of CXC chemokines are important in the pathogenesis of pulmonary fibrosis and other fibroproliferative disorders. In this Review, we discuss the biology of CXC chemokine family members, specifically as it relates to their role in regulating vascular remodeling and trafficking of circulating mesenchymal progenitor cells (also known as fibrocytes) in pulmonary fibrosis.

Cancer CXC chemokine networks and tumour angiogenesis

Chemokines have pleiotropic effects in regulating immunity, angiogenesis, stem cell trafficking, and mediating organ-specific metastases of cancer. In the context of angiogenesis, the CXC chemokine family is a unique group of cytokines known for their ability to behave in a disparate manner in the regulation of angiogenesis. The glutamic acid-leucine-arginine (ELR+) CXC chemokines are potent promoters of angiogenesis, and mediate their angiogenic activity via signal-coupling of CXCR2 on endothelium. By contrast, members of the CXC chemokine family, such as platelet factor-4 (PF4; CXCL4) and interferon-inducible CXC chemokines are potent inhibitors of angiogenesis, and use CXCR3 on endothelium to mediate their angiostatic activity. This review will discuss the biology of CXC chemokines in the context of angiogenesis related to cancer.

CXC chemokines in angiogenesis

CXC chemokines display pleiotropic effects in immunity, regulating angiogenesis, and mediating organ-specific metastases of cancer. In the context of angiogenesis, CXC chemokines are a unique family of cytokines, known for their ability to behave in a disparate manner in the regulation of angiogenesis. Members that contain the 'ELR' motif are potent promoters of angiogenesis, and mediate their angiogenic activity via binding and activating CXCR2 on endothelium. In contrast, members, in general, those are inducible by interferons and lack the ELR motif (ELR-) are potent inhibitors of angiogenesis, and bind to CXCR3 on endothelium. This review will discuss the biology of these angiogenic and angiostatic CXC chemokines and discuss their disparate angiogenic activity in the context of a variety of disorders.

Use of Immunodeficient Mice for the Evaluation of CXC Chemokines in the Regulation of Tumor-associated Angiogenesis

Angiogenesis, defined as the growth of new capillaries from pre-existing vessels, is a pervasive biological phenomenon that is at the core of many physiologic and pathologic processes such as tumor growth. The use of human tumor xenografts in immunodeficient mice has provided significant insight into the biology of angiogenesis as it relates to tumor growth and metastasis. Work reviewed in this article supports the notion that net tumor-derived angiogenesis during tumorigenesis of human tumors is determined, in part, by an imbalance in favor of the overexpression of angiogenic (compared with angiostatic) juxtaposed cysteine residue (CXC) chemokines. This paradigm predicts an environment that favors angiogenesis (tumorigenesis) and supports the potential for spontaneous metastases. The article describes the use of immunodeficient mice as an animal model system for characterizing the qualitative and quantitative presence of these angiogenic and angiostatic CXC chemokines during tumorigenesis, as well as determining their net contribution to human tumorigenesis and metastasis in vivo. Various cancer cell lines have been used and xenografted into immunodeficient mice to create human tumor/mouse chimeras, indicating that an imbalance in the biology of angiogenic versus angiostatic CXC chemokines supports a significant portion of human tumor-derived angiogensis that leads to augmented tumorigenesis and spontaneous metastases. It has also been possible to identify potentially therapeutic novel strategies to manipulate the imbalance of angiogenic (compared with angiostatic) CXC chemokines, which may be directly translational to human disease.