Wogonin suppresses tumor growth in vivo and VEGF-induced angiogenesis through inhibiting tyrosine phosphorylation of VEGFR2
Introduction
Angiogenesis, the formation of new blood vessels, is a fundamental step in physiologic processes, such as wound healing, organ growth and reproduction, as well as in pathological conditions like tumor progression, metastasis, chronic inflammation and arthritis (Folkman, 1971, Folkman, 1995, Folkman and Chesney, 1997, Hanahan and Folkman, 1996, Risau, 1997). To some extent, tumor growth is dependent on angiogenesis. An avascular tumor can rarely increase in size > 2–3 mm3. Once vascularized, a tumor grows rapidly and nearly exponentially. The newly generated blood vessels are required to supply adequate oxygen and nutrition to the growing tumor mass, and for initiation of metastatic spread (Folkman and Klagsbrun, 1987, Kerbel and Folkman, 2002). The angiogenic process is a highly complex, dynamic process regulated by a number of pro- and antiangiogenic molecules. The process of tumor angiogenesis involves recruitment of sprouting vessels from existing blood vessels and incorporation of endothelial progenitors into the growing vascular bed (Rafii et al., 2002). Events included in this process are the proliferation, migration and invasion of endothelial cells, organization of endothelial cells into functional tubular structures, maturation of vessels, and vessel regression.
Studies of the molecular basis of angiogenesis have identified a number of growth factor receptor pathways that promote tumor angiogenesis. One of the major pathways involved in this process is the vascular endothelial growth factor (VEGF) family of proteins and receptors. Vascular endothelial growth factor (VEGF) is one of the most important proangiogenic factors, which acts as a mitogen for vascular endothelial cells in vitro and as an angiogenic factor in vivo (Ferrara, 1996). It is overexpressed in various human cancers (Macchiarini et al., 1992, Paley et al., 1997, Weidner et al., 1991, Weidner et al., 1993). VEGF ligands mediate their angiogenic effects via several different receptors. Two receptors were originally identified on endothelial cells and characterized as the specific tyrosine kinase receptors VEGFR-1 (also referred to a fms-like tyrosine kinase 1 [Flt-1]) (Shibuya et al., 1990) and VEGFR-2 (also referred to as KDR (Terman et al., 1992), and the murine homologue, Flk-1) (Matthews et al., 1991). Inhibition of VEGF activity by neutralizing antibodies or the introduction of dominant negative VEGF receptors into endothelial cells of tumor-associated blood vessels often results in inhibition of tumor growth or even tumor regression (Kim et al., 1993).
Wogonin (C16H12O5) (Fig. 1), a naturally occurring monoflavonoid extracted from Scutellariae radix (Chi et al., 2001), has been shown to be a promising candidate for selective and effective management of human cancers (Tai et al., 2005). For example, wogonin inhibited the growth of human ovarian cancer cell A2780 (Li et al., 2003), human promyeloleukemic cell HL-60 (Lee et al., 2002, Yu et al., 2005), human hepatocellular carcinoma cell SK-HEP-1 (Chen et al., 2002) and human hepatoma cell SMMC-7721 (Wang et al., 2006a). Our previous study also showed that wogonin treatment resulted in significant inhibition of murine sarcoma S180 both in vitro and in vivo (Wang et al., 2006b). However, the molecular mechanism of its potent anticancer activity remains poorly understood and warrants further investigation. Though research has shown that wogonin can inhibit inflammation-stimulated angiogenesis, whether it can suppress the VEGF-stimulated angiogenesis remains unknown.
In this study, we assessed the antitumor effect on nude mice and antiangiogenic activity of wogonin in vitro and in vivo, and also investigated its effect on VEGF signal transduction.
Section snippets
Materials
Wogonin was isolated from Scutellaria baicalensis Georgi according to the protocols reported previously with slight modifications (Hui et al., 2002). S. baicalensis Georgi was bought from Yiling Medicine Co., LTD (Shijiazhuang, Hebei). The root of S. baicalensis Georgi was ground into powder, and 250 g of the resulting powder was extracted three times, each time with 1 l of dichloromethane, at room temperature. The extract was filtered through filter paper and concentrated to 100 ml in a rotary
Wogonin inhibits the growth of transplantable tumors
Tumor xenografts transplanted by human gastric carcinoma SGC-7901 cells were used to evaluate the antitumor effect of wogonin in vivo. The tumor volume in wogonin- or CTX-treated mice was less than that in negative control mice at the same measurement day (Fig. 2A). Values of T/C in the 60, 30, 15 mg/kg wogonin group were 20.6, 23.7, 30.9% (day 2), 20.8, 17.3, 51.6% (day 4), 18.9, 20.4, 48.2% (day 6), 23.0, 28.6, 51.6% (day 8), 27.0, 34.9, 60.5% (day 10) and 24.0, 40.1, 58.8% (day 12),
Discussion
In the recent years, traditional Chinese herbal remedies have gradually gained considerable attention as a new source of anticancer drugs. Extracts of the radix of the traditional Chinese herb S. baicalensis Georgi are among the most popular herbal remedies used in China and several oriental countries for clinical treatment of hyperlipemia, atherosclerosis, hypertension, dysentery, common cold and inflammatory diseases such as atopic dermatitis. Wogonin is a flavonoid derived from the root of
Acknowledgements
This work was supported by the National Natural Science Foundation of China (No. 30701032 and No. 90713038).
References (49)
- et al.
Inhibition of endothelial cell migration, intercellular communication, and vascular tube formation by thromboxane A(2)
Journal of Biological Chemistry
(1999) - et al.
Vascular endothelial growth factor effect on endothelial cell proliferation, migration, and platelet-activating factor synthesis is Flk-1-dependent
Journal of Biological Chemistry
(1999) - et al.
Effects of wogonin, a plant flavone from Scutellaria radix, on skin inflammation: in vivo regulation of inflammation-associated gene expression
Biochemical Pharmacology
(2003) Vascular endothelial growth factor
European Journal of Cancer
(1996)- et al.
Free radical scavenging and antioxidant activities of flavonoids extracted from the radix of Scutellaria baicalensis Georgi
Biochimica Biophysica Acta
(1999) - et al.
Patterns and emerging mechanisms of the angiogenic switch during tumorigenesis
Cell
(1996) Dimerization of cell surface receptors in signal transduction
Cell
(1995)- et al.
Anxiolytic effect of wogonin, a benzodiazepine receptor ligand isolated from Scutellaria baicalensis Georgi
Biochemical Pharmacology
(2002) - et al.
Vascular endothelial growth factor and its receptors
Cytokine & Growth Factor Reviews
(1996) - et al.
Sphingosine 1-phosphate induces angiogenesis: its angiogenic action and signaling mechanism in human umbilical vein endothelial cells
Biochemical and Biophysical Research Communications
(1999)
Wogonin and fisetin induce apoptosis in human promyeloleukemic cells, accompanied by a decrease of reactive oxygen species, and activation of caspase 3 and Ca(2+)-dependent endonuclease
Biochemical Pharmacology
Endostar, a novel recombinant human endostatin, exerts antiangiogenic effect via blocking VEGF-induced tyrosine phosphorylation of KDR/Flk-1 of endothelial cells
Biochemical and Biophysical Research Communications
Antiviral Chinese medicinal herbs against respiratory syncytial virus
Journal of Ethnopharmacology
Relation of neovascularisation to metastasis of non-small-cell lung cancer
Lancet
High affinity VEGF binding and developmental expression suggest Flk-1 as a major regulator of vasculogenesis and angiogenesis
Cell
A novel type of vascular endothelial growth factor, VEGF-E (NZ-7 VEGF), preferentially utilizes KDR/Flk-1 receptor and carries a potent mitotic activity without heparin-binding domain
Journal of Biological Chemistry
Identification of the KDR tyrosine kinase as a receptor for vascular endothelial cell growth factor
Biochemical and Biophysical Research Communications
Different signal transduction properties of KDR and Flt1, two receptors for vascular endothelial growth factor
Journal of Biological Chemistry
Vascular permeability factor (VPF)/vascular endothelial growth factor (VEGF) peceptor-1 down-modulates VPF/VEGF receptor-2-mediated endothelial cell proliferation, but not migration, through phosphatidylinositol 3-kinase-dependent pathways
Journal of Biological Chemistry
Identification of a peptide blocking vascular endothelial growth factor (VEGF)-mediated angiogenesis
EMBO Journal
Wogonin and fisetin induction of apoptosis through activation of caspase 3 cascade and alternative expression of p21 protein in hepatocellular carcinoma cells SK-HEP-1
Archives of Toxicology
Effect of wogonin, a plant flavone from Scutellaria radix, on the suppression of cyclooxygenase-2 and the induction of inducible nitric oxide synthase in lipopolysaccharide-treated RAW 264.7 cells
Biochemical Pharmacology
The second immunoglobulin-like domain of the VEGF tyrosine kinase receptor Flt-1 determines ligand binding and may initiate a signal transduction cascade
EMBO Journal
Vascular permeability factor/vascular endothelial growth factor: a critical cytokine in tumor angiogenesis and a potential target for diagnosis and therapy
Journal of Clinical Oncology
Cited by (87)
Identification of multi-target anti-cancer agents from TCM formula by in silico prediction and in vitro validation
2022, Chinese Journal of Natural MedicinesAn-te-xiao capsule inhibits tumor growth in non-small cell lung cancer by targeting angiogenesis
2018, Biomedicine and PharmacotherapyEnhancement of solubility and dissolution rate of baicalein, wogonin and oroxylin A extracted from Radix scutellariae
2017, International Journal of Pharmaceutics
- 1
These two authors contributed equally to this article.