• Archives of Pharmacal Research
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• v.28 no.11
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• pp.1270-1274
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• 2005

The vascular endothelial growth factor (VEGF) plays a key role in angiogenesis, which is a process where new blood vessels develop from the endothelium of a pre-existing vasculature. VEGF exerts its activity by binding to its receptor tyrosine kinase, KDR/Flk-1, which is expressed on the surface of endothelial cells. A methanol extract and organic solvent (n-hexane, ethyl acetate, n-butanol, aqueous) fractions from Rubus coreanus were examined for their inhibitory effects on VEGF binding to the VEGF receptor. The methanol extract from the crude drug were found to significantly inhibit VEGF binding to the VEGF receptor ($IC_{50}$$\thickapprox$27 $\mu$g/mL). Among the fractions examined, the aqueous fraction from the medicinal plant showed potent inhibitory effects against the binding of KDR/Flk-1-Fc to immobilized $VEGF_{165}$ in a dose­dependent manner ($IC_{50}$$\thickapprox$11 $\mu$g/mL). Sanguiin H-6 was isolated as an active principle from the aqueous fraction, and inhibited the binding of KDR/Flk-1-Fc to immobilized $VEGF_{165}$ in a dose­dependent manner ($IC_{50}$$\thickapprox$0.3 $\mu$g/mL). In addition, sanguiin H-6 efficiently blocked the VEGF­induced HUVEC proliferation in a dose-dependent manner ($IC_{50}$$\thickapprox$7.4 $\mu$g/mL) but had no effect on the growth of HT1080 human fibrosarcoma cells. This suggests that sanguiin H-6 might be a potential anti-angiogenic agent.

• Natural Product Sciences
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• v.13 no.2
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• pp.128-131
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• 2007

Tumor angiogenesis is a critical step f3r the growth and metastasis of solid tumors. Vascular endothelial growth factor (VEGF) is the most important angiogenic molecule associated with tumor-induced neovascularization. VEGF exerts its activity through binding to its receptor tyrosine kinase, KDR/Flk-1, expressed on the surface of endothelial cells. This study was carried out to investigate inhibitory effect of extracts from root cortex of Paeonia suffruticosa Andrews on VEGF binding to VEGF receptor. The MeOH extract from P. suffrutiocosa Andr. inhibited the binding of KDR/Flk-1-Fc to immobilized VEGF$_{165}$ more than 45% at the concentration of 100 ${\mu}$g/mL. The MeOH extract was further fractionated into n-hexane, ethyl acetate, n-BuOH, and aqueous fractions. Among the four fractions, the ethyl acetate fraction from the root cortex of P. suffruticosa Andr. exhibited highly effective inhibition (${\approx}$ 79% inhibition) and then n-BuOH fraction (${\approx}$ 45% inhibition) on the binding of KDR/Flk-1-Fc to immobilized VEGF$_{165}$ at the concentration of 100 ${\mu}$g/mL. The ethyl acetate fraction from the root cortex of P. suffruticosa Andr. more efficiently blocked VEGF-induced human umbilical vein endothelial cell proliferation, than the growth of HT1080 human fibrosarcoma. Our results suggest that P. suffruticosa Andr. may be used as a candidate fur developing anti-angiogenic agent.

• Journal of Acupuncture Research
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• v.26 no.1
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• pp.153-162
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• 2009

목적 : 한의학 분야에서 육계(CCE: Cinnamomum cassia)는 혈류 순환이 저하된 상태에 널리 쓰이는 약재이다. 이 연구에서는 CCE와 그 활성 혼합물인 cinnamic acid가 in vitro와 in vivo에서 발휘하는 신생혈관 형성 작용에 대해 알아보고자 한다. 방법 : CCE와 CA의 신생혈관형성 작용을 알아보기 위하여 Human unbilical endothelial cells(HUVECs)와 Bovine arterial endothelial cells(BAECs) 그리고 Matrigel assay를 이용하였다. 결과 : In vitro에서 CCE와 그 활성 혼합물은 HUVEC 증식, 이동, 모세혈관-유사 관 형성을 유도한다. CCE에서의 25-50% 증가(1 또는 10ng/ml 용량에서)는 CA에서 증식과 유사하게 나타났다. HUVEC에서는 증식이 뚜렷하게 나타났으나 BAEC에서는 증식이 뚜렷하게 나타나지 않아 증식 효과는 내피세포의 기원에 따라 다른 것으로 나타났다. BAEC는 CCE와 CA에서 증식은 보이지 않았지만 이동과 모세혈관-유사 관 형성 또는 분화를 보였다. 또한 CCE와 CA는 HUVEC에서 VEGF 발현과 Flk-1/KDR 발현을 각각 2.2배와 2.5배 증가시켰다. 결론 : CCE와 그 활성 혼합물은 in vivo와 in vitro에서 혈관 내피세포의 VEGF 발현을 통하여 신생혈관 형성 작용을 유도하며 이는 앞으로 다른 한약 추출물의 신생혈관형성 촉진 작용 연구에 모델을 제시할 것으로 보인다.

• Korean Journal of Medicinal Crop Science
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• v.15 no.5
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• pp.311-314
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• 2007

Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are the most important angiogenic molecules associated with tumor-induced neovascularization. This study was carried out to investigate inhibitory effect of extracts from root of Rehmannia glutinosa LIBOSCHITZ (Rehmannia Radix and Rehmannia Radix Preparata) on endothelial cell proliferation. The methanol extracts from the medicinal herb were fractionated into n-hexane, ethyl acetate, n-butanol and aqueous fractions. Among the four fractions, the n-butanol fraction from R. Radix on exhibited highly effective inhibition (${\approx}79%$ inhibition) on the binding of KDR/Flk-1-Fc to immobilized $VEGF_{165}$ and then ethyl acetate fraction from R. Radix (${\approx}45%$ inhibition) at the concentration of $100\;{\mu}g/ml$. The n-butanol fraction efficiently blocked the VEGF- and bFGF-induced HUVEC proliferation in a dose-dependent manner, but did not affect the growth of HT1080 human fibrosarcoma cells. The n-butanol fraction more efficiently blocked the binding of KDR/Flk-1-Fc to immobilized $VEGF_{165}$ and VEGF- and bFGF-induced human umbilical vein endothelial cell proliferation than the fraction from R. Radix Preparata. Our results suggest that Rehmannia Radix may be used as a candidate for developing anti-angiogenic agent.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.9-15
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• 2011

The functional cardiovascular system is comprised of distinct mesoderm-derived lineages including endothelial cells, vascular smooth muscle cells and other mesenchymal cells. Recent studies in the human embryonic stem cell differentiation model have provided evidence indicating that these cell lineages are developed from the common progenitors such as hemangioblasts and cardiovascular progenitor cells. Also, the studies have suggested that these progenitors have a common primordial progenitor, which expresses KDR (human Flk-1, also known as VEGFR2, CD309). We demonstrate here that sustained activation of BMP4 (bone morphogenetic protein 4) in hESC line, CHA15 hESC results in $KDR^+$ mesoderm specific differentiation. To determine whether the $KDR^+$ population derived from hESCs enhances potential to differentiate along multipotential mesodermal lineages than undifferentiated hESCs, we analyzed the development of the mesodermal cell types in human embryonic stem cell differentiation cultures. In embryoid body (EB) differentiation culture conditions, we identified an increased expression of $KDR^+$ population from BMP4-stimulated hESC-derived EBs. After induction with additional growth factors, the $KDR^+$ population sorted from hESCs-derived EBs displays mesenchymal, endothelial and vascular smooth muscle potential in matrix-coated monolayer culture systems. The populations plated in monolayer cultures expressed increased levels of related markers and exhibit a stable/homologous phenotype in culture terms. In conclusion, we demonstrate that the $KDR^+$ population is stably isolated from CHA15 hESC-derived EBs using BMP4 and growth factors, and sorted $KDR^+$ population can be utilized to generate multipotential mesodermal progenitors in vitro, which can be further differentiated into cardiovascular specific cells.

• The Journal of Korean Society for Radiation Therapy
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• v.14 no.1
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• pp.165-174
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• 2002

Vascular endothelial growth factor (VEGF) has been identified as a peptide growth factor specific for vascular endothelial cells. In this study, we examined the effect of VEGF on radiation induced apoptosis and receptor/second messenger signal transduction pathway for VEGF effect in human umbilical vein endothelial cells (HUVECs). VEGF was found to protect HUVECs against the lethal effects of ionizing radiation by inhibiting the apoptosis induced in these cells by radiation exposure. VEGF (1-30 ng/ml) dose dependently inhibited apoptosis by irradiation. Pre-treatment with Flt-1 and Flk-l/KDR receptor blocked the VEGF-in duced antiapoptotic effect. Phosphatidylinositol 3'-kinase (PI3-kinase) specific inhibitor, Wortman in and LY294002, blocked the VEGF-induced antiapoptotic effect. These data suggest that VEGF may play an important role in survival of HUVECs due to the prevention of apoptotic cell death caused by some stresses such as ionizing radiation.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.4
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• pp.307-313
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• 2008

Purpose: Vascular endothelial growth factor (VEGF) and its receptor, fetal liver kinase 1 (Flk-1), play an important role in vascular permeability and tumor angiogenesis. The aim of this study is to evaluate the therapeutic efficacy of $^{131}I$ labeled anti-Flk-1 monoclonal antibody (DC101) on the growth of melanoma tumor, which is known to be very aggressive in vivo. Materials and Methods: Balb/c nude mice were injected subcutaneously with melanoma cells in the right flank. Tumors were allowed to grow up to $200-250\;mm^3$ in volume. Gamma camera imaging and biodistribution studies were performed to identify an uptake of $^{131}I$-DC101 in various organs. Mice with tumor were randomly divided into five groups (10 mice per group) and injected intravenously; control PBS (group 1), $^{131}I$-DC101 $50\;{\mu}g/mouse$ (group 2), non-labeled DC101 $50\;{\mu}g/mouse$ (group 3), $^{131}I$-DC101 $30\;{\mu}g/mouse$ (group 4) and $15\;{\mu}g/mouse$ (group 5) every 3 or 4 days for 20 days. Tumor volume was measured with caliper twice a week. Results: In gamma camera images, the uptake of $^{131}I$-DC101 into tumor and thyroid was increased with time. Biodistribution results showed that the radioactivity of blood and other major organ was gradually decreased with time whereas tumor uptake was increased up to 48 hr and then decreased. After 4th injection of $^{131}I$-DC101, tumor volume of group 2 and 4 was significantly smaller than that group 1. After 5th injection, the tumor volume of group 5 also significantly reduced. Conclusion: These results indicated that delivery of $^{131}I$ to tumor using FlK-1 antibody, DC101, effectively blocks tumor growth in aggressive melanoma xenograft model.

• BMB Reports
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• v.39 no.5
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• pp.469-478
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• 2006

Vascular endothelial growth factor (VEGF)-A, a major regulator for angiogenesis, binds and activates two tyrosine kinase receptors, VEGFR1 (Flt-1) and VEGFR2 (KDR/Flk-1). These receptors regulate physiological as well as pathological angiogenesis. VEGFR2 has strong tyrosine kinase activity, and transduces the major signals for angiogenesis. However, unlike other representative tyrosine kinase receptors which use the Ras pathway, VEGFR2 mostly uses the Phospholipase-$C{\gamma}$-Protein kinase-C pathway to activate MAP-kinase and DNA synthesis. VEGFR2 is a direct signal transducer for pathological angiogenesis including cancer and diabetic retinopathy, thus, VEGFR2 itself and the signaling appear to be critical targets for the suppression of these diseases. VEGFR1 plays dual role, a negative role in angiogenesis in the embryo most likely by trapping VEGF-A, and a positive role in adulthood in a tyrosine kinase-dependent manner. VEGFR1 is expressed not only in endothelial cells but also in macrophage-lineage cells, and promotes tumor growth, metastasis, and inflammation. Furthermore, a soluble form of VEGFR1 was found to be present at abnormally high levels in the serum of preeclampsia patients, and induces proteinurea and renal dysfunction. Therefore, VEGFR1 is also an important target in the treatment of human diseases. Recently, the VEGFR2-specific ligand VEGF-E (Orf-VEGF) was extensively characterized. Interestingly, the activation of VEGFR2 via VEGF-E in vivo results in a strong angiogenic response in mice with minor side effects such as inflammation compared with VEGF-A, suggesting VEGF-E to be a novel material for pro-angiogenic therapy.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.6
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• pp.528-534
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• 2005

Angiogenesis is important for the growth and metastasis of solid tumors. Some growth factors, inflammatory cytokines, and angiogenin are known to promote tumor angiogenesis. Among them, Vascular endothelial growth factor (VEGF) is the most intriguing factor in regard to tumor angiogenesis. Inhibition of VEGF activity by neutralizing antibodies or by the introduction of dominant negative VEGF receptors into endothelial cells of tumor-associated blood vessels resulted in the inhibition of tumor growth and in tumor regression, indicating that VEGF is a major initiator of tumor angiogenesis. VEGF promotes angiogenesis through their receptors, Flt-1 and Flk-1/KDR. on vascular endothelial cells. These two receptors were usually believed to be expressed specifically on vascular endothelial cell. Several reports have now shown that VEGF is not only significantly associated with microvessel density but also has prognostic value in both node-negative and node-positive oral squamous cell carcinoma. For many years several histologic features of the neoplasms are being considered when assessing the influence of malignancy grading on recurrence and prognosis. Among the characteristics investigated, degree of keratinization, nuclear pleomorphism, mode of invasion, microscopic depth of invasion, intravascular invasion, lymphocyte infiltration, and number of mitoses have been considered as important prognostic factors. So, this study was conducted to evaluate the correlation of vascular endothelial growth factor expression with malignancy in paraffin-embedded biopsy specimens from 11 patients with tongue cancers. Our results showed that high immunoreactivity specimens of VEGF expression were significantly lower keratinization degree and more pronounced nuclear pleomorphism than in low immunoreactivity specimens. Thus, VEGF expression could be used as a prognostic marker in tongue cancer.