Biomedical subjects

Tsutomu Oikawa

Publications and source records attributed to Tsutomu Oikawa.

8 recordsLinked to original sources

PubMed2006

Inhibition of in vivo angiogenesis by N-beta-alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine.

N-beta-alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD), an antibacterial substance isolated from the flesh fly, inhibits human tumor growth in the nude mice model; however, the mechanism of its action is unclear. The in vivo antitumor effect includes the inhibition of tumor cell proliferation and suppression of angiogenesis. Angiogenesis is essential for tumor growth in vivo. In this study, we examined whether 5-S-GAD inhibits tumor cell-induced angiogenesis by performing the mouse dorsal air sac assay. We found that intraperitoneal administration of 5-S-GAD inhibited the angiogenesis induced by S180 mouse sarcoma cells. Furthermore, 5-S-GAD also inhibited vascular endothelial growth factor-induced angiogenesis in the Matrigel plug assay and embryonic angiogenesis in the chick embryo chorioallantoic membrane assay. However, 5-S-GAD did not show any effect on the proliferation, migration, and tube formation of vascular endothelial cells. These results provide the first evidence that a bioactive substance derived from the flesh fly has antiangiogenic activity in vivo, although the mechanisms involved could not be explained.

Angiogenesis Inhibitors↗

PubMed2006

Suppression of laser-induced choroidal neovascularization by subconjunctival injection of 9alpha-fluoromedroxyprogesterone acetate (FMPA), an anti-angiogenic agent, in rats.

9alpha-Fluoromedroxyprogesterone acetate (FMPA) is a synthetic analog of medroxyprogesterone acetate (MPA). FMPA exhibited more potent anti-tumor and anti-angiogenic activities in some assay systems than the parent agent, MPA. Exudative age-related macular degeneration (AMD) is characterized by choroidal neovascularization (CNV). Anecortave acetate, an angiostatic steroid, is clinically efficacious in patients with exudative AMD. Betamethasone is an anti-angiogenic steroid. Therefore, we examined the effects of FMPA, anecortave acetate and betamethasone on laser-induced CNV in rats. Anecortave acetate and betamethasone were included as positive controls. Crypton laser was applied to the fundus in Brown Norway rats. Laser photocoagulations were performed in each eye between the major retinal vessels of the superior retina. Subconjunctival injection of FMPA, anecortave acetate or betamethasone was performed once just after the photocoagulation (on day 0). The incidence of CNV formation was evaluated by fluorescein angiography (FAG) on day 14. On the next day, examination of the retinal function was performed by electro retinogram (ERG). Subconjunctival injection of FMPA at doses of 300, 1000 and 3000 microg/eye dose-dependently inhibited the incidence of CNV formation. Significant differences were observed at doses of 1000 and 3000 microg/eye of FMPA as compared with the control group. Anecortave acetate and betamethasone significantly inhibited the incidence of CNV formation. FMPA at the doses used in this study did not affect the retinal function in rats, as determined by ERG. FMPA appeared to be effective in a rat model of CNV, so it was demonstrated that FMPA might be useful in the treatment of AMD.

Angiogenesis Inhibitors↗

PubMed2006

Synthesis and anti-tumor activity of a fluorinated analog of medroxyprogesterone acetate (MPA), 9alpha-fluoromedroxyprogesterone acetate (FMPA).

We synthesized 9alpha-fluoromedroxyprogesterone acetate (FMPA) in order to test whether it is a more potent anti-angiogenic agent than medroxyprogesterone acetate (MPA), which has been widely used as a therapeutic agent for breast and endometrium cancers. FMPA was previously synthesized in 10 steps (total yield: 1%). An efficient synthesis of FMPA has been achieved in 6 steps (total yield: 12%). We examined the anti-tumor effect of FMPA, complexed with dimethyl-beta-cyclodextrin (DM-beta-CyD), on rat mammary carcinomas induced by 7,12-dimethylbenz[a]anthracene (DMBA). FMPA showed great anti-tumor effect on DMBA-induced rat mammary carcinomas.

Administration, Oral↗

PubMed2004

Bovine lactoferrin inhibits tumor-induced angiogenesis.

Recent studies have demonstrated that bovine lactoferrin (bLF) suppresses tumor growth and metastasis in the mouse and rat and moreover may inhibit angiogenesis. To determine whether angiogenesis inhibition might contribute to antitumor activity, we examined the influence of bLF on tumor-induced angiogenesis and endothelial cell functions as well as angiogenesis-related cytokine production. Bovine LF exhibited dose-dependent inhibition of angiogenesis on 4-6-day-old chick embryo chorioallantoic membranes (CAMs) that lack a mature immune response. This inhibition was reversed when bLF was simultaneously treated with basic fibroblast growth factor (bFGF). It also inhibited in vitro formation of tube-like structures of mouse endothelial KOP2.16 cells. Moreover, it potently suppressed bFGF- or VEGF-induced proliferation of mouse endothelial KOP2.16 cells, but not of mouse fibroblast A31 cells and Lewis lung carcinoma (3LL) cells. In mice, both orally and intraperitoneally administered bLF significantly and dose-dependently suppressed 3LL cell-induced angiogenesis in a dorsal air sac assay. As orally administered bLF was reported to exhibit antitumor activity through production of interferon (IFN)-gamma and interleukin (IL)-18 in intestinal mucosa (Kuhara T et al., Nutr Cancer 2000;38:192-9), production of these cytokines in mouse serum and peritoneal macrophages by bLF was examined. IFN-gamma was not detected in serum by bLF administration. However, bLF markedly elevated IL-18 concentration in serum by oral administration, but not by intraperitoneal administration. It also induced IL-18 in peritoneal macrophages in vitro. These results suggest that bLF participates as a regulator of angiogenesis, possibly explained by blocking endothelial function and inducing IL-18 production. Antitumor activity of bLF may thus be partly mediated by angiogenesis inhibition.

Administration, Oral↗

PubMed2004

Directed biosynthesis of fluorinated pseurotin A, synerazol and gliotoxin.

Aspergillus fumigatus TP-F0196 produces pseurotin A, synerazol and gliotoxin. Phenylalanine is a common biosynthetic precursor of these antibiotics. Feeding fluorophenylalanine to the culture induced the production of novel fluorinated analogs. These fluorinated antibiotics were obtained from the culture broth by solvent extraction and purified by chromatographies, and their antimicrobial and antitumor activities were investigated. Among the novel fluorinated analogs, 19- and 20-fluorosynerazols exhibited potent anti-angiogenic activity in the chorioallantoic membrane assay. In addition, 19-fluorosynerazol showed more potent cytocidal activity against several cancer cell lines than synerazol.

Angiogenesis Inhibitors↗

PubMed2003

Effects of rhizoxin, a microbial angiogenesis inhibitor, on angiogenic endothelial cell functions.

Our previous study revealed that rhizoxin ([1S-[1R*,3R*,5S*,8R*(1R*,2S*,3E,5E,7E),10R*,11S*,13S*,14E,16S*,17S*]]-10-hydroxy-8-[2-methoxy-1,3,7-trimethyl-8-(2-methyl-4-oxazolyl)-3,5,7-octatrienyl]-11,16-dimethyl-4,7,12,18-tetraoxatetracyclo[15.3.1.03,5.011,13]heneicos-14-ene-6,19-dione) has a potent inhibitory effect on in vivo angiogenesis. However, little is known regarding the mechanism by which rhizoxin exhibits antiangiogenic activity. In this study, we examined its effects on the functions of endothelial cells associated with neovascular formation in vivo, using cultured vascular endothelial cells. Rhizoxin concentration-dependently inhibited the proliferation of bovine carotid artery endothelial cells, human umbilical vein endothelial cells and human dermal microvascular endothelial cells, the IC(50) values being 7, 5 and 0.4 nM, respectively. In addition, it reduced the extracellular plasminogen activator level in bovine vascular endothelial cells in the low nM range, and suppressed the migration of human dermal microvascular endothelial cells in the pM range. Furthermore, it blocked the tubular morphogenesis of human umbilical vein endothelial cells and human dermal microvascular endothelial cells on Matrigel in a concentration-dependent manner; the IC(50) values being 40 and 130 pM, respectively. These results suggest that rhizoxin exhibits antiangiogenic activity through the combined inhibition of some functions of endothelial cells responsible for induction of in vivo angiogenesis.

Angiogenesis Inhibitors↗

PubMed2003

Preliminary studies on the anti-angiogenic potential of pomegranate fractions in vitro and in vivo.

We previously showed pomegranate seed oil and fermented juice polyphenols to retard oxidation and prostaglandin synthesis, to inhibit breast cancer cell proliferation and invasion, and to promote breast cancer cell apoptosis. Here we evaluated the anti-angiogenic potential of these materials in several ways. We checked a possible effect on angiogenic regulation by measuring vascular endothelial growth factor (VEGF), interleukin-4 (IL-4) and migration inhibitory factor (MIF) in the conditioned media of estrogen sensitive (MCF-7) or estrogen resistant (MDA-MB-231) human breast cancer cells, or immortalized normal human breast epithelial cells (MCF-10A), grown in the presence or absence of pomegranate seed oil (SESCO) or fermented juice polyphenols (W). VEGF was strongly downregulated in MCF-10A and MCF-7, and MIF upregulated in MDA-MB-231, overall showing significant potential for downregulation of angiogenesis by pomegranate fractions. An anti-proliferative effect on angiogenic cells was shown in human umbilical vein endothelial cell (HUVEC) and in myometrial and amniotic fluid fibroblasts, and inhibition of HUVEC tubule formation demonstrated in an in vitro model employing glass carrier beads. Finally, we showed a significant decrease in new blood vessel formation using the chicken chorioallantoic membrane (CAM) model in vivo. 'In sum, these varied studies employing different models in different laboratories overall demonstrate for the first time an anti-angiogenic potential of pomegranate fractions, suggesting further in vivo and clinical investigations (for updates: info@rimonest.com).

Angiogenesis Inhibitors↗

PubMed2003

Novel function of ascorbic acid as an angiostatic factor.

Endothelial permeability is increased by vascular endothelial cell growth factor and decreased by antioxidants. Whether or not l-ascorbic acid (Asc), which decreases endothelial permeability by stimulating the endothelial barrier function, is anti-angiogenic (angiostatic) remains unknown. We examined the role of Asc on angiogenesis using two assay systems. At first, the potential role of Asc on four steps of angiogenesis was investigated in cultured bovine microvascular endothelial cells. Asc inhibited the formation of vessel-like tubular structures of endothelial cells cultured on Matrigel; however, it did not decrease the activity of plasminogen activator (PA), which creates the space into which vascular vessels extend. Furthermore, even at high concentrations, Asc did not inhibit either the proliferation or migration of endothelial cell cultures. Secondly, whether Asc inhibited in vivo angiogenesis or not was studied on chick chorioallantoic membrane (CAM) during the 4-6 days of embryogenesis when neovascularization is rapid. It also revealed that angiogenesis was dose-dependently inhibited by Asc from 0.5 micro mol/CAM with half-maximal inhibition at 2.5 micro mol/CAM. Because it was previously reported that the endothelial barrier function decreases permeability via the stimulation of collagen synthesis induced by Asc, we treated CAM with the inhibitor of collagen synthesis, l-azetidine 2-carboxylic acid (AzC). This compound partially attenuated the angiostatic function of Asc on CAM. To understand the involvement of an antioxidant activity in the angiostatic function of Asc, we further examined the effect of glutathione (GSH), which is an endogenous antioxidant, on angiogenesis in CAM and endothelial cells. GSH inhibited CAM angiogenesis, as well as the formation of vessel-like tubular structures of endothelial cell cultures on Matrigel. Both Asc and GSH inhibited hydrogen peroxide (H(2)O(2)) induced tubular morphogenesis. These findings suggest that Asc affects angiogenesis through both its antioxidant properties and the stimulation of collagen synthesis. As the angiostatic activity of Asc may be one of the many effects involved in host resistance to the growth or invasiveness of solid cancer, it may be useful as a supplementary therapy in various angiogenic diseases.

Angiogenesis Inhibitors↗